This is an update of the situation as of 10 am JST Wednesday 16 March. (For background on events of 15 March and earlier, start with this post and its included links.) Note that this is a blog, not a news website, and thus the following analysis, like all others on BraveNewClimate, is a mixture of news and opinion — but facts remain paramount.

First, the situation is clearly (but slowly) stabilising. As each day passes, the amount of thermal heat (caused by radioactive decay of the fission products) that remains in the reactor fuel assemblies decreases exponentially. When the reactors SCRAMed on 11 March after the earthquake, and went sub-critical, their power levels dropped by about 95 % of peak output (the nuclear fission process was no longer self-sustaining). Over the past 5 days, the energy in the fuel rods dropped by another ~97 %, such that the heat dissipation situation is getting more and more manageable. But we’re not out of the woods yet, and the reactor cores will need significant cooling for at least another 5 days before stability can be ensured.

Yesterday there appears to have been a fracture in the wetwell torus (see diagram: that circular structure below and to the side of the reactor vessel) in Unit 2, caused by a hydrogen explosion, which led to a rapid venting of highly radioactive fission product gases (mostly noble [chemically unreactive] gases, the majority of which had a half-life of seconds to minutes). It also caused a drop in pressure in the supression pool, which made the cooling process more challenging. However, despite some earlier concerns, it is now clear that containment was not breached. Even under this situation of extreme physical duress, the multiple containment barriers have held firm. This is an issue to be revisited, when the dust finally settles.

Units 1 and 3, the other two operating reactors at Fukushima Daiichi when the earthquake struck, continue to be cooled by sea water. Containment is secure in both units. However, like Unit 2, there is a high probability that the fuel assemblies have likely suffered damage due to temporary exposure (out of water), as the engineers struggled over the last few days to maintain core coolant levels. Whether there has been any melting of the clad or rods remains unclear, and probably will continue to be shrouded in a cloud of uncertainty for some time yet.

The other ongoing serious issue is with managing the heat dissipation in the spent fuel ponds. These contain old fuel rods from previous reactor operation that are cooling down, on site, immersed in water, which also provides radiation shielding. After a few years of pond cooling, these are transferred to dry storage. The heat in these rods is much less than those of the in-core assemblies, but it is still significant enough as to cause concern for maintaining adequate coverage of the stored fuel and to avoid boiling the unpressurised water. There have been two fires in Unit 4, the first tentatively linked to a failed oil pump, and the second, being of (currently) unknown cause, but the likelihood is that it was linked to hydrogen gas bubbling.

There appears to have been some exposure of this spent fuel, and radiation levels around this area remain high — making access in order to maintain water levels particularly troublesome. Note that apart from short-lived fission product gases, these radiation sources are otherwise contained within the rods and not particularised in a way that facilitates dispersion. Again, the problems encountered here can be linked to the critical lack of on-site power, with the mains grid still being out of action. As a further precaution, TEPCO is considering spraying the pool with boric acid to minimise the probability of ‘prompt criticality’ events. This is the news item we should be watching most closely today.

This figure illustrates the current reported state of the Daiichi and Daini reactors, last updated 1230 on 16 March (click to enlarge):

The status report from the The Federation of Electric Power Companies of Japan (FEPC) is given below:

• Radiation Levels

o At 10:22AM (JST) on March 15, a radiation level of 400 milli sievert per hour was recorded outside secondary containment building of the Unit 3 reactor at Fukushima Daiichi Nuclear Power Station.

o At 3:30PM on March 15, a radiation level of 596 micro sievert per hour was recorded at the main gate of Fukushima Daiichi Nuclear Power Station.

o At 4:30PM on March 15, a radiation level of 489 micro sievert per hour was recorded on the site of the Fukushima Daiichi Nuclear Power Station.

o For comparison, a human receives 2400 micro sievert per year from natural radiation in the form of sunlight, radon, and other sources. One chest CT scan generates 6900 micro sievert per scan.

• Fukushima Daiichi Unit 1 reactor

o As of 10:00PM on March 14, the pressure inside the reactor core was measured at 0.05 MPa. The water level inside the reactor was measured at 1.7 meters below the top of the fuel rods.

• Fukushima Daiichi Unit 2 reactor

o At 6:14AM on March 15, an explosion was heard in the secondary containment building. TEPCO assumes that the suppression chamber, which holds water and stream released from the reactor core, was damaged.

o At 1:00PM on March 15, the pressure inside the reactor core was measured at 0.608 MPa. The water level inside the reactor was measured at 1.7 meters below the top of the fuel rods.

• Fukushima Daiichi Unit 3 reactor

o At 6:14AM on March 15, smoke was discovered emanating from the damaged secondary containment building.

• Fukushima Daiichi Unit 4 reactor

o At 9:38AM on March 15, a fire was discovered on the third floor of the secondary containment building.

o At 12:29PM on March 15, TEPCO confirmed extinguishing of the fire.

• Fukushima Daini Units 1 to 4 reactors: all now in cold shutdown, TEPCO continues to cool each reactor core.

This indicates a peak radiation level of 400 mSv/hr, which has come down to about 0.5 mSv/hr by the afternoon. This ‘spot’ radiation level was measured at a location between Unit 3 and 4. It was attributted to a hydrogen explosion in the spent fuel pool of Unit 4 — but this is still under debate. The radiation level at the site boundary is expected to have been much lower and, to date, there is no risk to the general public.

What is known is that this is a situation very different than Chernobyl or Three Mile Island. There was no operator error involved at Fukushima-Daiichi, and each reactor was successfully shut down within moments of detecting the quake. The situation has evolved slowly but in a manner that was not anticipated by designers who had not assumed that electrical power to run emergency pumps would be unavailable for days after the shutdown. They built an impressive array of redundant pumps and power generating equipment to preclude against this problem. Unfortunately, the tsunami destroyed it.

There are some characteristics of a nuclear fission reactor that will be common to every nuclear fission reactor. They will always have to contend with decay heat. They will always have to produce heat at high temperatures to generate electricity. But they do not have to use coolant fluids like water that must operate at high pressures in order to achieve high temperatures. Other fluids like fluoride salts can operate at high temperatures yet at the same pressures as the outside. Fluoride salts are impervious to radiation damage, unlike water, and don’t evolve hydrogen gas which can lead to an explosion. Solid nuclear fuel like that used at Fukushima-Daiichi can melt and release radioactive materials if not cooled consistently during shutdown. Fluoride salts can carry fuel in chemically-stable forms that can be passively cooled without pumps driven by emergency power generation. There are solutions to the extreme situation that was encountered at Fukushima-Daiichi, and it may be in our best interest to pursue them.

More updates as further information comes to hand. Otherwise, for me, it’s back to the mad TV and radio media circus.

Chief Cabinet Secretary Yukio Edano had outlined problems that had occured on the morning of 16 March with Fukushima Daiichi 3 and 4.

At 8:34am local time white smoke was seen billowing out of Fukushima Daiichi 3. Efforts to determine the cause of this development were interrupted as all workers had evacuated to a safe area due to rising radiation readings. Readings from a sensor near the front gate had fluctuated for some time, although Edano said that on the whole there was no health hazard. Earlier in the morning readings had ranged between 600-800 microsieverts per hour, but at 10am readings rose to 1000 microsieverts per hour. Readings began to fall again from around 10:54.

Edano said that one possibility being considered was that the unit 3 reactor had suffered a similar failure to that suffered by unit 2 yesterday, although there had been no reported blast or loud sound, which had been the case for unit 2. The immediate focus, said Edano was on monitoring of levels and checking pumping operations.

Edano also outlined plans for units 4-6. Preparations were being made to inject water into unit 4, however the high levels of radiation from unit 3 were imparing those preparations. When possible, the water injection would be done gradually as there were safety concerns over pouring a large amount of water at once. The water will be pumped into the reactor building from the ground, plans to drop water from a helicopter having been abandoned. Although he said that “all things were possible” Edano did not believe that recriticality at unit 4 was a realistic risk

Second fire at unit 4

Earlier, the Nuclear and Industrial Safety Agency said that a blaze was spotted in the reactor building of Fukushima Daiichi 4 at 5.45am local time this morning.

Attempts to extinguish it were reportedly delayed due to high levels of radiation in the area. A spokesperson for TEPCO said that by around 6:15am there were no flames to be seen.

The incident at unit 4 is believed to be in the region of a used fuel pond in the upper portion of the reactor building.

Origins

Tokyo Electric Power Company issued a notice of an explosion at unit 4 at 6am on 15 March. This was followed by the company’s confirmation of damage around the fifth floor rooftop area of the reactor building.

On that day, a fire was discovered but investigations concluded it had died down by around 11am.

At present it is not clear whether today’s fire was a completely new blaze, or if the fire reported yesterday had flared up again.

According to the IAEA, unit 4 was shutdown for routine maintenance and refuelling on 30 Nov 2010 and all the fuel core (548 fuel assemblies) transfered to the SF pond. Units 5 and 6, although shutdown, have the fuel back in the core, so there will only be about third of the core spent fuel from refuelling in their SF ponds. Similarly for units 1-3, I would expect there to be SF from the last refuelling in the reactor SF pond as most of the previous SF will have been transfered to the shared SF pond. This may explain why unit 4 reactor SF pond is more sensitive to loss of normal cooling.

After reading the factsheet you suggested by NEI, it seems to suggest only when core temperature rise to above 1k C will suffient hydrogen be generated to have cause an explosion.

If the source of the second explosion at No. 4 Reaction is indeed due to hydrogen build up, does that imply the spent fuel rods are fairly new and in your opinion what kind of further degradation will we expect? Do correct me if i have some of my concepts wrong

Just to add on. If on the other hand, the spent rods are still submerged with the temperature of the water being at the reported temperature of around 80 degree C and the cause of the 2nd explosion is found to be hydrogen build up. I would like to ask why would hydrogen dissociation occur at such a high rate to cause hydrogen gas build up if the temperature of water is at such low level (relatively).

Curiously, fixation on the broken nuclear reactor simply because it’s radioactive. The whole affair really shows how fragile the built world is in the face of perfectly natural forces. The faces of Venus and Mars show that what we call the biosphere is probably a temporary phenomenon.

As do individual human creatures, the biosphere as a whole will die someday. It’s all really in the natural order of things.

The TepCo guys were on the news a few minutes ago.
They clearly stated that, over the night the radiation levels reached a maximum of 1000 mSv/h and they stressed the fact they are talking about mili not micro.
during the course of the night the radiation levels seemed to stabilize around an average of 600 mSv/h.
Also as of this morning, the readings at the main gate of the plant, not the reactors are in mSv/h but did not say the exact amount. They just said we are counting levels of radiation near the main gate in mili seivert units.
Clearly, if the above statements are true, then they totally contradict your estimation that radiation went back down to 0.5mSv/h in the afternoon.

So with a radiation dose of 400 milli sievert per hour recorded outside secondary containment building of the Unit 3 reactor at Fukushima Daiichi Nuclear Power Station, and a chest CT scan giving a dose of 6.9 milli sieverts each … then the radiation rate outside unit 3 was equivalent to 58 CT scans an hour (400/6.9) or nearly one per minute). Yikes.

Ya, I just heard on NHK, that they detected radiation levels of 1000 mSv/h. It looks like there is “white smoke” coming out of reactor 3. I’ve seen reports that it could be either the spent fuel ponds or damage to the reactor vessel.

I’ll add my thanks for the update, Barry. Good to get some actual facts about the situation…
I was in equal parts amused and disgusted by the front page reporting in The Australian today – particularly the bit where an “expert” stated that the safe dosage is only 1 milliSievert.
The layout of some of the media stories is dodgy, at best – I saw one story entirely about the nuclear situation, with casualty figures from the quake+tsunami inserted out-of-context into the middle. A quick perusal of the article would lead a careless reader to think that thousands of people had been killed by radiation!

I thought the supression pool was used as a source of spray water for the BWR, thus the water would contain absorbed radioactive isotopes of I and Cs and the long lived Strontium. Given the exposure of the fuel rods at one point, or even the lack of flow of coolant causing melting of the Zr casing, the fissile materials emitted from the UO2 increases. Thus the problem appears greater than during a usual failure. We have a double failure scenario.

sorry, wrong link. So it looks like the 1000mSv/h happened yesterday, but currently in conjunction with the white smoke, the radiation levels are in the “milli range.” This value is supposed to be decreasing now.

Barry, I don’t think technical detail is relevant. What puzzles and annoys me is that it happened. What does this say about human capacity to plan, design and manage. They knew the site was prone to earthquakes and tsunamis, and possible consequences such as loss of power for cooling systems. Did they ignore this, or did they fail to take it into account properly; one or the other. I would have thought the nuclear industry would have made super-sure that something like this could not happen; or is it that they can’t do so. (The fact that the reactors are old is not crucial; they chose to continue running them and that’s a comment on mangement wisdom too.) To me the main implication seems to be this kind of event is part of the nuclear package, given that highly fallible humans make the decisions. If you want nuclear energy then you’d better accept this kind of event now and then. I don’t think humans can be trusted to run such things well…evetywhere, all the time…when you’d need maybe 20,000 of them to provide all people with our lifestyle.

Speaking as an advocate of nuclear power, there needs to be a worldwide moratorium on all new construction of nuclear power plants for a minimum of two years. Time that should be used by the broadest possible selection of experts to sort out the weaknesses in safety that were exposed in Fukushima.

It’s interesting to note how the information flow by English press websites of the key Japanese organizations starting from TEPCO itself has collapsed since yesterday morning and they now resort to releasing all public information via TV conferences.

For example, they showed the following picture (showing the damage to reactor buildings 3 and 4) to TV cameras, but no high resolution file available anywhere:

I came here for a scientific perspective, but I seem to be getting a near fatal dose of competing Ideologies instead. I am seeing the reports here on American TV that the workers have abandoned the plant. I don’t have any technical expertise on the matters discussed, but I rue the lack of objectivity I have seen here through recent days. It feels like the normal vicious U.S, political blog back and forth BS and competing agenda promotion. Why no clarification on the plant abandonment issue? That doesn’t sound like good news. Will somebody spin that?

Levels overnight were apparently ~1 mSv/h (1,000 uSv), and declined to 600-800 uSv/h this morning at the front gate. However, just after 10 am local time that level rose sharply (to an unspecified number), forcing the evacuation of personnel. Levels declined somewhat in the hour after that time.

Considering that they were measuring 1 mSv/h at the front gate, I wonder what the levels are in the actual work areas.

Acc. to those on the Something Awful forum, the evacuation news is reportedly a couple of hours old and it has been confirmed that workers have been allowed to return. The evac. order was given because of some mis-readings. Not sure what sources they are quoting for this.

Man, this is getting head-snapping. Here’s what seems the central statement from the author of that MIT student newspaper article Mr. Brook linked to:

“… the situation is under control, it is unlikely that the nuclear fuel has melted, the risk to the public is effectively zero, and, depending on whether facts on the ground have been reported correctly, it is possible that the reactors will remain capable of producing power in the future.”

Well of course “depending on whether the facts on the ground have been reported correctly” it may be that no earthquake or tsunami has even occurred. And as to the rest, not only has damn near every report indicated that at least some fuel has melted, but to have said that the situation is “under control” is just laughable given the new report that they have just evacuated the plant because it’s too dangerous for anyone to be trying to do anything in same.

“[N]ear fatal dose of competing ideologies” indeed, as rpl has said, or at least a heaping big dose of over-confidence.

Amazes me that even given the wild, utterly unexpected events of the last couple of days, and the clearly wild uncertainty that still exists, how people will just go about willy-nilly putting their names on the line instead of just saying “who the hell knows what might happen?”

At this point then what I at least would regard as the smartest commentary would concentrate on just telling us the parameters of the possible: What’s the best possible theoretical outcome, and what’s the worst?

Now *that’s* something that would seem to have some credibility. In my opinion at least everything else has just been proven to pretty much be baloney, within hours if not minutes.

(This said, still gotta say I love this site and have great respect for the host and the great majority of commentators. I have no problem with speculation; it’s over-confidence in projections that make me wince.)

American, on 16 March 2011 at 2:23 PM — Read the article linked in my previous comment from WNN; it seems the workers have now returned.

I’m just an amateur at this, but as best as I can make out units 1, 2 and 3 are now finished generating and will have to be disposed of, eventually. It appears to me that TEPCO is trying hard to save unit 4; it remains unclear whether that will be possible. Units 5 & 6 will be fine provided TEPCO can, quite soon, arrange for makeup water and appropriate cooling of the spent fuel pools of those shut-down reactors.

I’m not in a position to have that much confidence in my reading of events, but there it is.

Just to clarify the topic of the generator use from reactor 6 for reactor 5 cooling water level adjustment.
The Nuclear and Industrial Safety Agency says the coolant level has fallen in the No.5 reactor at the Fukushima Daiichi nuclear power plant.
The Agency had earlier said the No.5 reactor stopped safely during a regular inspection when the massive earthquake and tsunami occurred on Friday.
At the time of the quake, nuclear fuel rods were already in the reactor and workers had to circulate water to cool them down.
But the tsunami damaged a diesel generator for circulating the coolant, allowing the pressure in the reactor to rise.
Workers opened a valve to reduce the pressure.
But the procedure allowed water to evaporate from the valve.
As of 9 PM on Tuesday, the water level was 2 meters above the fuel rods. That was 40 centimeters lower than 5 hours earlier.
The Agency says it can adjust the water levels by using the No.6 reactor’s generator, which wasn’t damaged by the tsunami. Workers are currently pumping water into the No.5 and No.6 reactors.

The container of the No.3 reactor of the quake-hit Fukushima No.1 nuclear power plant is feared to have been damaged and may have leaked radioactive steam Wednesday, emitting high-level radiation, Chief Cabinet Secretary Yukio Edano said.

I suppose for me the idea expressed in this post that “there was no operator error” (and the human errors were design errors, in a sense, failures of imagination), so everything is somehow a-okay, is not particularly satisfying to me. The designers failed to envision an exceptional event, yet one happened. It is true that the plant is performing beyond its design capabilities, yet _at best_ this event/accident is comparable in scale to only a handful of nuclear/radiological events in the past. Long-term consequences are still unclear (and may well remain unclear for many years). Is a failure of imagination a satisfying excuse?

In any case, at 10:40 am levels at the front gate spiked to 10 mSv/h (10,000 uSv/h), which dropped to 2.7 mSv/h (2,700 uSv/h) by 11:10 am.

There is no mention of an erroneous instrument reading leading to this spike (which presumably triggered the evacuation). One would hope that there are enough instruments in place to rule out inexplicable measurement error.

It’s strange that they would pull the remaining crews out after just receiving a lift in the authorized total dose from 100 mSv to 250 mSv for carrying out the emergency coolant injection and firefighting efforts.

I sure hope they are using any time of total evacuation to bring in fresh shifts from other TEPCO plants (Daini as the closest with stable situation) or even plants of other companies.

Because there is really no such option as abandoning the plants, because that would almost guarantee that they all burn to the ground and a large fraction of their total radionuclide inventories get released. Besides, there are about 5 more cores worth of spent fuel in the secondary cooling pool facility and the new dry storage facility.

The worst case scenario of the whole plant area is left to burn, is a release of possibly several orders of magnitude more radiation as from Chernobyl. It was estimated that at most 4% of the Chernobyl 4 load of 150 tons was released in the environment, while there are over 4,000 tons of fuel at Fukushima Daiichi, based on March 2010 public inventory of total spent fuel storage and the loaded cores of the 6 reactors (reactor 4 load in the SFP).

I’m not saying that the worst case scenario is credible, only that there is no way the Japanese government would completely abandon even extraordinary attempts to bring the fires and cooling failures under control.

“There is no mention of an erroneous instrument reading leading to this spike (which presumably triggered the evacuation). One would hope that there are enough instruments in place to rule out inexplicable measurement error.”

One explanation given to the lack of usually reliable real time radiation measurements is that the normal dose rate stations have all failed since their battery backup ran out and the only monitoring being done is by a car that drives between the monitoring stations and sends data from short stops at each post.

Red_Blue, if all your guys are already at, close to, or past 100 mSv, and you get the government to allow 250 mSv, that gives you 150 mSv left to work with.

When just standing at the front gate (to say nothing of the actual work area) gives you a dose of 2-10 mSv/hour, that gives your workers only 15-75 hours before they’re legally “dosed” again. It seems to make sense to pull them back to minimize their exposure during particularly high periods of time.

Why not let the rods in the reactor core melt, bottle up the concrete (fail-safe outer containment unit, collect the melt in the concrete containment, focus in on making sure the spent water pools remain full with water, and come in a few years time for the now solidified melted rods? Wouldn’t this address the problem?

I realize this would be going into uncharted territory, a hail-Mary pass so to speak. After all that was what the concrete containment was designed for.

An entire train full of people disappeared in the tsunami, and yet no civilians have been killed by the radiation leaking from this plant. Since there is no anti-train lobby freaking out about that “failure of imagination”, people like Barry have to put this situation in the proper scientific context.

Buildings crush people in earthquakes, but no one calls for a moratorium on buildings, do they? No, we build safer ones. That will happen with nuclear power once the hysteria subsides, perhaps once energy prices start to skyrocket. Nothing is 100% safe, so we might as well enjoy the affordable power while driving our electric cars on a highway system that kills tens of thousands per year.

Red_Blue wrote,
“One explanation given to the lack of usually reliable real time radiation measurements is that the normal dose rate stations have all failed since their battery backup ran out and the only monitoring being done is by a car that drives between the monitoring stations and sends data from short stops at each post.”

I suppose I do not find that explanation particularly convincing. Even in the “car” scenario, multiple instruments and/or at least multiple measurements seems eminently possible. If their mobile monitoring contingency plan is one guy with an uncalibrated G-M counter and no spare batteries in a 1989 Honda, the situation is even more disastrous than any of us had previously imagined.

In the wake of the Fukushima incident, it has really helped me to understand what happened in 1979 at Three Mile Island, with nonsense all throughout the media, and FUD, and panic spreading, with good information almost impossible to find, with the over-abundance of bad information leading to hysteria.

But this is the first time it has happened to the Facebook and Twitter generation; I’ve yet to determine whether that’s a good thing or a bad thing. We need to keep working hard to make sure it’s a net benefit for the good information, not the dodgy information.

“The worst case scenario of the whole plant area is left to burn … [but] there is no way the Japanese government would completely abandon even extraordinary attempts to bring the fires and cooling failures under control.”

Ah, thank you Red_Blue for giving what does indeed on reflection seem the worst case. Thank you very much indeed.

I do have a further question though: Just how “extraordinary” could the government get? I mean … how could it order people in to do something there when that would likely mean certain death?

I have no doubt there’s already been heroes over there who have sacrificed themselves, and indeed anyone working there right now seems to me to qualify for that honor anyway. But thing can always get worse, right? I.e., even more certainly lethal.

Seems to me to maybe argue for the Japanese gov’t not to wait too long to take whatever further action it can to help. (Such as trying to order in troops to do so.) It’s one thing to issue such an order when there’s just the possibility of death/sickness, it’s another whole ball of wax when that’s a virtual certainty.

Wonder if now’s the time, esp. given the likely breach of containment?

Though I understand where you’re coming from, as I posted above (for it is indeed my post, it seems that there are two posters posting as ‘Mike’), comparing the death toll from the earthquake/tsunami and the current issues at Fukushima Daiichi, to me, borders on the absurd. At the very least, it’s a flawed metric to use at this point in time (maybe in thirty or fifty years it will be more appropriate, but even then I imagine it will be difficult to deconvolute the specific effects of whatever additional dosage results from this event).

Much ink has been spilled on the issue of the risks of a modern society (including buildings, transportation, and power generation) and “acceptable” levels of risk; I am not an expert on the subject. But, indeed, as you point out, there were design failures in other arenas as well (e.g., buildings, transit systems). I can’t really comment on the cost (including risks)/benefit analyses associated with those.

“I do have a further question though: Just how “extraordinary” could the government get? I mean … how could it order people in to do something there when that would likely mean certain death? ”

I don’t image them ordering anyone to certain death, even the soviets didn’t go that far. However, I would expect them to order TEPCO and the other Japanese nuclear power companies assign personnel to Fukushima, so that experienced and trained crew can be rotated to keep their doses below even radiation sickness levels (1 Sv).

Work can be accomplished in quite high radiation environments with a large enough crew and good coordination. History of reactor and research criticality accidents have some pretty harrowing rescues and retrievals of bodies or equipment from places where one could get a fatal dose in matters of hours. The way to cope is to spread the dose among a group of volunteers, each working like a runner in a relay race, going quickly in, doing a small part of the task, then running out, with the next guy (or a small team such as a pair or two pairs etc.) going in. Each person would do only one run and then be replaced or relegated to support duties.

“It’s basically a sign that there’s nothing left to do but throw in the towel,” Lochbaum said.

Lochbaum was identified in the story as a “nuclear engineer who now heads the nuclear safety program for the Union of Concerned Scientists, an activist group that opposes the expansion of nuclear power.

I guess Lochbaum is getting pretty confident he’ll be able to offer comment as the world ends, soon.

Some of this stuff is good for a laugh. This morning I heard one breathless podcaster telling the world that because sea level would rise 1 foot by 2050, reactors located close to the sea must now be assumed to be at risk – and obviously for this and the many other reasons he offered, it was well past time the world should prohibit nuclear power.

I don’t like the sound of guys getting orders or volunteering to be the guy who goes where it is death to go to do the vital thing. I hope it isn’t coming to that anywhere in this mess.

“I don’t image them ordering anyone to certain death, even the soviets didn’t go that far.”

Just to clarify that, I meant during the Chernobyl accident and really, they didn’t order anyone to a task that was known to a high degree of certainty to result in a fatal dose. Some level of negligence existed in properly estimating the risks and also the initial response was highly uncoordinated. But they didn’t cold heartedly calculate some “acceptable loss of life” and then plan their operations based on that criteria.

BNC is a little haven of rationality and information amidst the sound bites and dross of mainstream media. Thanks Barry and others sharing their knowledge and experience.

Luke: I’ll be interested in the “fall out” amongst the twitter generation. I was 25 at the time of TMI and firmly anti-nuclear but have no clear memory of the event. My life was filled with other concerns. If you asked me a few years back what happened at TMI my recollection would have been completely and utterly wrong. I suspect most Australians without a strong interest will just be letting the evening news wash over them and will form totally false memories of this event. It would be useful to run a poll in 6 months to test what people got from mainstream coverage … it won’t be pretty!

Hi. Does anyone know if they are using seawater to cool the spent fuel in #4 and the reactors in 5 and 6? I imagine that the salt would flaw the reactor enough to where they couldn’t use it in the future (without SIGNIFICANT restructuring). I just wondered if they were ready to scrap the whole plant or if they are hoping it won’t get worse and worse and worse..
There are many people here who say that this isn’t as serious as others make it out to be, and vice versa.. but consider that there has never been a time in our (world) history when multiple reactors have been at risk. containment systems can fail just like cooling systems can. This is a horrible tragedy, and one we can learn from. I support nuclear energy, but like any technology we should certainly respect it’s dangers.

His most recent claim to fame was a rather notorious article claiming that allowing gays into the military would weaken US armed forces (http://tech.mit.edu/V131/N9/dadtpro.html) among other conservative-leaning political articles (http://tech.mit.edu/author/Keith+Yost/). He is not written elsewhere on scientific topics, and he apparently left a post-undergraduate gig in Dubai for the Boston Consulting Group under a cloud (which he wrote about in a series of articles last year).

Is this really the kind of fact-based, objective, authoritative source you want to be presenting to your readers?

After just Googling around I see just now that Edano has broached the idea of sending in some of Japan’s military, and some high Japanese official has now noted his government’s potential to ask the U.S. military in to help.

American wrote,
“After just Googling around I see just now that Edano has broached the idea of sending in some of Japan’s military, and some high Japanese official has now noted his government’s potential to ask the U.S. military in to help.”

Japan’s SDF (“Self-Defense Force,” the Japanese equivalent of a military) is already on-scene, and has been actively participating. So I’m really not sure what you mean…?

Interesting post, I was thinking pretty much the same thing. I remember TMI quite well, because I was going to university in eastern Canada at the time. I knew nothing about radiation except it was bad. And, I knew that if President Carter or the Pennsylvania Governor was going to call an evacuation, I was going to high tail it back to western Canada to get out of the way of the prevailing winds. I didn’t give a damn if I had to forfeit my tuition fees. I just picked up that panic from the news situation at the time.

But, I see that panic now in man-on-the-street interviews with people in Japan leaving Tokyo and heading to the southern part of Japan. I can sympathize.

However, since, TMI (and Chernobyl) I have had the opportunity to be taught by some really great physics profs and did some self-learning to the point I wouldn’t have any qualms about sitting tight in the zone 20-30 km out from the Fukushima plant until this situation is resolved.

It really is about education. Educating people about doses and what they mean, putting the doses into context. Unfortunately, people would rather sit in front of their computer/TV monitor or game the stock market than educate themselves. And, then when something like this happens it is too late to educate them on the basics.

If people do want to start and become educated on radiation and nuclear reactors, a good spot to go is Dr. Richard Muller’s Physics for the General Student at the Univ. of Berkeley http://www.youtube.com/watch?v=EVB0F7kORII
see Lectures 5,6, 7 and 8.

I am still of the mind that nuclear power is our best option to combat global warming. The German experiment with solar and wind has shown that those sources just aren’t ready for prime time, or else why would they have fallen back to building coal-fired power plants.

Nonetheless, the panic and mass hysteria component to this incident is, from an academic point-of-view, very interesting.

Mike: I didn’t know that the SDF were already there and so when I just read that Edano had apparently talked about sending in SDF *helicopters* I thought this was the first potential appearance of the Japanese military. Sorry.

Allright, I’ll play a bit – DV82XL I appreciate that you have come out as a major stakeholder on the nuclear power side. Perhaps others knew that already, but newcomers to this blog (such as I) are just now figuring it out for sure. It seems that the line of argument has morphed from “there is not a real problem” to “the problem doesn’t really matter” to “it can’t happen here”. Good to know where you stand , though I can see the sand shifting under your feet.
Susanne, good spinning. but somehow I am not reassured by the contention that the Japanese company in charge of these failing nuclear reactors can not even measure radioactivity reliably. I am not necessarily anti nuclear energy, despite living 5 miles from the largest Nuclear weapon storage facility in the U.S.A. And despite having witnessed an actual Mushroom cloud in the Nevada desert in the 1950’s. I am trying to keep an open mind. but disingenuity on this thread is not making that very easy.

Hank: MIT student/nuclear engineer/staff member Yost’s opinion piece about how “Global warming not worth the fight” (http://tech.mit.edu/V130/N45/yost.html) is even more enlightening and probably also of interest to readers of this blog:

“Global warming is real. It is predominantly anthropogenic. Left unchecked, it will likely warm the earth by 3-7 C by the end of the century. What should the United States do about it?

“Very little, if anything at all.” . . . .

“To act unilaterally, or even in conjunction with the rest of the developed world, would mean paying the full measure of mitigating climate change while receiving only a fraction of its benefit.”

A conservative (as in right wing) Australian blogger makes the comparison with the Hiroshima bomb. Extreme perhaps. However on the basis of the long term radation impact of that bomb event says that the media is over hyping this current nuclear event completely.

Barry: I have to say I’m confused by the apparent deletion of my post about Keith Yost, whom you (unintentionally, I’m sure) misrepresent as a MIT staff member.

How are readers to gauge the authenticity of the material on this site if you don’t allow them to gauge the authority (or lack thereof) of the sources?

I honestly felt that my post was a corrective, not an accusatory one, and I included a number of links to support each of my statements about his background. Yost is a political writer, not a science writer; he is a student, not a staff member. These are relevant facts.

@T-Squared “The German experiment with solar and wind has shown that those sources just aren’t ready for prime time, or else why would they have fallen back to building coal-fired power plants.”

Just found bravenewclimate during this Fukushima incident, so my reply to your comment is very off-topic, but I’d say compare solar incidence in Germany with that in the US and ask why utility-scale solar and wind are not viable sources of 100’s GW’s. Maybe this has been discussed in another area of the blog?

TerjeP – As a rule I think it is great to have Bolt reference this blog on occasions, but not to return the favour… nasty man nasty blog. He also prefers the studies that suggest there was no such thing as a stolen generation and that Aborigninal folks have it all on a taxpayer funded platter. He is not a friend of science by any stretch of the imagination.

While it’s likely only a point measurement, this link shows a 3.4 mSv/hour dose rate at the power station boundary. To me, that qualifies as “serious”, particularly since the dose rate is likely higher as one gets closer to the source.

@rpl – When I wrote my last comment I was writing as a Canadian, not as a stakeholder in the nuclear industry. Click on my name for my full profile, I have no other interest in the nuclear industry beyond, my considered opinion that it the only available technology that can supply us with clean energy in the future

The US military will reportedly be using pumper trucks to send water into units 3 and 4 for cooling. If that isn’t enough, it appears that they’ve gone back to the helicopter idea, but with hoses this time. That ought to be quite a sight. Unfortunately, it appears that blizzard/snow storm conditions might put a damper on the helicopter option.

“As a further precaution, TEPCO is considering spraying the pool with boric acid to minimise the probability of ‘prompt criticality’ events. This is the news item we should be watching most closely today.”
WTF ? How is even possible for reaching prompt critical ?
Even with full meltdown of nuclear materials reching critical should be impossible. Has to be.
So far it looks Japans underestimated the situation and used too few and not well-equipped people to handle the crysis.
70 people? To maintain cooling in 6 damaged reactors + pools with fuel?
70 would be enough when everything functions, not now. These people can’t work for more than several hours in the zone, there must be fast rotation of personel.
(In Chernobyl soldiers were used to “collect and drop” hot nuclear material from the roof into the exposed core. Due to extremely high doses, one had to run, collect anything and go back in 30 seconds and thousands were used. Still there were dead, including the commanding officer, but they did what had to be done)

On a related note, please correct me if I’m wrong but it seems that by going with the “hose it down from a distance” option there is an implicit admission of containment rupture. Otherwise I see no way to possibly get water into a pressurized and sealed enclosure with a hose. Physics would protest.

Just a reminder that this situation at Tokushima is not as a result of a nuclear “accident” (as were Chernobyl and TMI) caused by human error, mismanagement or faulty design. That the 40 year old utility has stood up so well to the massive onslaught of record breaking(at least for Japan) natural disasters which wiped out all the usual utilities (power, water, etc.) designed to provide back-up is surely a testament to the designers and engineers. To the people labouring to contain any further damage I think we should all say a heartfelt thank you.

Great effort Barry. Keep up the good work. I am starting to detect the media’s disappointment that the operators and technicians at Fukushima actually manage to keep things from getting worse ,against all odds.

Does human error in the form of designer error count? The plant was not designed for an event which did in fact occur–could you explain to me how this is not an “accident”?

In a sense I will acknowledge that it is in fact “intentional”, in that the facility was intentionally not designed for an event which did occur, but I don’t see how that’s a satisfying justification for anything. In fact, from that perspective it’s a powerful indictment of the designers.

But we absolutely agree in that the people laboring at the site deserve the highest form of honor possible. They are true heroes (and, like many heroes, will probably only admit to doing their job).

Barry: there is a difference between thermal heat of the reactor fuel and the temperature of the reactor fuel that your readers may not appreciate.

While it is certainly true that the thermal heat (energy) of the fuel decreases exponentially each day there is still a huge amount of potential energy in the system. The short-term danger is that the workers at the plant do not have good control of the TEMPERATURE of the fuel and its surroundings.

They are venting radioactive steam in attempts to regain control of the temperature.

“On a related note, please correct me if I’m wrong but it seems that by going with the “hose it down from a distance” option there is an implicit admission of containment rupture. Otherwise I see no way to possibly get water into a pressurized and sealed enclosure with a hose.”

Perhaps the reason is that they are now shifting priority to what remains of the spent fuel pools at the top of the reactor building remains of each reactor. If they can get the fuel rods at these locations covered with water, that would drive down the activity in the immediate environment and then perhaps allow turning attention back to the reactor vessels at each unit.

I’m wondering which US unit would be in a position to provide fire trucks with sufficient capacity. The closest I can think of is the 374th Mission Support Group with their heavy airbase ARFF vehicles, but they are based in Yokota, some 200 miles away.

Sorry, I accidentally hit “Post comment” before I finished. They are indeed based at Yokota, but apparently there are some pumper trucks in the vicinity of Fukushima Daiichi, and TEPCO people were instructed in their use by the folks at Yokota.

I am posting this link and quote to counter Jim Green’s outrageous claim of hundreds of thousands of deaths from radiation exposure near Chernobyl (on his current Uleashed article) How does he get away with this?http://www.unscear.org/unscear/en/chernobyl.html
“The Chernobyl accident caused many severe radiation effects almost immediately. Of 600 workers present on the site during the early morning of 26 April 1986, 134 received high doses (0.8-16 Gy) and suffered from radiation sickness. Of these, 28 died in the first three months and another 19 died in 1987-2004 of various causes not necessarily associated with radiation exposure. In addition, according to the UNSCEAR 2008 Report, the majority of the 530,000 registered recovery operation workers received doses of between 0.02 Gy and 0.5 Gy between 1986 and 1990.”

The radiation dosage recieved by a person or other living thing or object is measured using a variety of units. Doses of radiation are measured in gray (Gy), sievert (Sv) or roentgen (R). These units are derived within the SI system (the roentgen is an older unit redefined in SI terms and accepted as an SI unit). The rad (radiation absorbed dose) and the rem (roentgen equivalent man) are derived from CGS (centimetre-gram-second) units. As we shall see, conversion between the old and modern units is straightforward.

Sievert (Sv):
The sievert is the SI unit for the dose equivalent, a measure of the biological effect of a given radiation dose. The dose equivalent in sieverts is obtained by measuring the radiation exposure in gray (Gy) and multiplying this value by two dimensionless constants, Q and N. Q corrects the dose according to the type of radiation in question. N is used to modify the result for the particular organ or kind of tissue exposed.

Roentgen (R):
1 roentgen is the amount of radiation required to liberate positive and negative charges of one electrostatic unit of charge (esu) in 1 cm^3 of dry air at standard temperature and pressure (STP). This corresponds to the generation of approximately 2.08×10^9 ion pairs. One rad is approximately equal to 1.07 roentgen. Conversly, one roentgen is approximately equivalent to 0.93 rad.

Rem (roentgen equivalent man/mammal):
The rem bears the same relation to the rad as the sievert to the gray, and is calculated with the same dimensionless constants.

1Sv = 100 rem.

Rep (Roentgen Equivalent Physical):
The rep is a unit of absorbed dose of ionising radiation equivalent to 93 ergs per gram. It is obselete and has been superseded by the rad.

CPM (Counts Per Minute) and DPM (Disintegrations per Minute):
Counts Per Minute is the number of atoms in a given quantity of radioactive material that are detected to have decayed in one minute. This is closely related to the unit Disintegrations Per Minute (DPM). DPM is a measure of radioactivity. It is the number of atoms in a given quantity of radioactive material that decay in one minute. One Bq = 60 DPM.
Counts per minute can be useful when detector efficiency is in question. For example, when a scintillator is designed to detect the 0.013 Mev photons from uranium 238 and one is measuring the 1.146 Mev photons from potassium 40, the units cannot be easily converted to roentgens. CPM is a more appropriate unit under such conditions.

“The gray is a unit used to measure physical quantity (e.g., ‘how much energy is deposited in the human body by radiation’). It is known, however, that biological effects of radiation on living beings vary depending on the types of radiation even if the same amount of energy (dose) is deposited. Sievert is used to complement this.

Sievert can be determined by the following formula:
Sievert = Biological effectiveness factor unique to the type of radiation * Gray”

“BTW check out the doses they received after Chernobyl – 0.8-16 Gy. Barry what is a Gy and how does it compare with the micro/milli sieverts being measured at Fukushima?”
Grays measure absorption doses and to get sieverts or other equivalent dose values, you need to apply the biological conversion factor.

One gray is a very large dose. If it’s gamma radiation or X-rays for example, it’s equivalent to 1,000 millisieverts or 1,000,000 microsieverts. The highest dose rate that has been reported for Fukushima has been 400 mSv/h, which would result in ARS (acute radiation poisoning) in about two hours of continuous exposure.

would all the water and flooding serve to spread contaminants further in the case of ejection of radioactive material from the plant? or would it serve to concentrate it to an area closer to the plant?

“Only when the radiation level reaches 1.5 million to 2 million microsievert does the person exposed get ill,” Wang added.

If the radiation level surpasses 2 million microsievert, then the people exposed to the radioactive source will become transmitters.

The Tokyo Electric Power Company said radiation leaking from the Fukushima Daiichi plant reached 8,217 microsievert an hour, more than eight times greater than the 1,000 microsievert people are naturally exposed to in a year, after a third explosion in four days rocked the plant Tuesday morning, according to Kyodo News .

As a precaution, the Japanese government told about 140,000 people living within 30 km of the plant to stay indoors to avoid radiation exposure, although the radiation levels were not high enough to pose a risk.”
I hope these facts allay the worries of of some people in Japan or who have friends and relatives there.

k0rd wrote,
“would all the water and flooding serve to spread contaminants further in the case of ejection of radioactive material from the plant? or would it serve to concentrate it to an area closer to the plant?”

Well, I would imagine that if the pools overflowed, there would at least be a plume of contaminated water moving downward from the immediate area of the reactors. Presumably once it hit the water table it would then migrate laterally with groundwater flow, potentially offsite. But that’s not an immediate threat, whereas the melting of the fuel rods is a fairly immediate threat.

Ms. Perps, the death count attributed to chernobyl does include deaths that can only statistically be linked to the event, like increased cancer rates.

If you go the way of ‘we only attribute what is directly caused by the event’ (like the cigarette industry likes to do), then I think it might almost be possible to argue that no one was killed by the chernobyl event as such, as opposed to stupidity/heroism in the cleanup afterwards.

Besides, the comparison to the tsunami victim count is a bit off, too. The tsunami isn’t man-made, the reactors are. People who got washed away in the trains would have the same fate if they were standing there instead. The people who got evacuated due would *not* have been evacuated if the reactors behaved well.

The BBC is reporting that helicopters have taken off to try to dump water/boron on the plant/pool.

A quick calculation in-the-head of the masses of any material a helicopter could deliver to target yields … yup, well … anyone else with some suggestions now the plant operators can’t be onsite? Robots? Anyone got any?

BTW, “stabilising”? “not out of the woods”?

I’ve been reading what you write since this developed Barry and I think your language is suitably changing, finally.

While the veracity is hard to confirm, it seems very difficult to understand how they could not have been more vigilant on problems with the pool in unit 4.

Shouldn’t they also have removed some of the side walls before they blew off in explosions, since they couldn’t evacuate hydrogen through pumps?

I understand that it’s a very trying task (though can’t image how much so), but some poor choices seem to have deteriorated conditions. In hindsight, perhaps given total blackout, operators should have accepted certain, manageable actions over risking structural integrity.

“A quick calculation in-the-head of the masses of any material a helicopter could deliver to target yields … yup, well … anyone else with some suggestions now the plant operators can’t be onsite? Robots? Anyone got any?”

I’ve already phoned my suggestions into HQ. They hung up on me. It’s just as well, I guess; the experts tell me there’s nothing to worry about anyway, so I’m sure everything will be fine. Note that my tongue is planted firmly in my cheek as I type this.

Seriously, though, apparently they have concocted a helicopter + hoses + pumper trucks plan, despite poor weather conditions (“fubuki” is Japanese for blizzard, for those of you playing disaster Bingo at home). I’m not exactly sure how that’s going to work, or how it’s going to work out. But we shall see, I suppose.

Pure conjecture on my part, but that might average out to ~3 mSv/hour at the gate, meaning about 75 mSv per day of exposure, just standing at the gate. Presumably the workers are wearing PPE that shields them somewhat, but they’re also closer to the source.

I’m curious, does anyone here (any health physicists around?) know anything about the shielding value of PPE? Generally for beta emitters a layer of thick plastic is useful shielding, but for gamma rays you start getting into the “thick blocks of lead” realm–which is obviously not practical as PPE. I’m sure they’re wearing respirators, but what about dose to the rest of the body?

Indeed they could have been more vigilant. A nuclear station without power is a ticking bomb. As ‘always’ when it comes to prompt by governments and politicians a common understanging has to be established, then approved by authorities etc. before anything get done.

Imo the situation could have looked alot different if they brought in sufficient means of power by saturday. That could be heavy duty generators, but i suggested a ship (or submarine for that case) on the site to deliver power and pumping capasity.

@spangled drongo: That’s chinese, as are the many deaths to coal miners. I’m pretty sure that I don’t want to see things that can explode just because they are left alone (and without grid) for some time in a country that has a history of preferring profit over safety.

Re seawater to I-4: supposedly there is no access to seawater there. The satellite imagery shows the ground between the sea and I-4 to have another building plan/piping layout than for I-1 to I-3, but the linear distance is the same. IONO how correct the info is thus.

Some imagery of Wednesday morning:
Looking along I-3 onto the N face of I-4:

Mike, the translation said Unit 3 but they must mean Unit 4. If they can get that pull fully covered again, they’ll be able to get in there and get the piping in place. Once all the SNF is fully covered again, the gammas will drop to virtually nothing.

Below is part of a post by “Michael R James” over on
Crikey.com, can someone who knows the engineering comment on the statement about
“low level fission”:

“The other thing Barry Brook probably regrets claiming, is that these containment vessels will contain the fuel no matter what. That is simply nonsense. I think it comes from the misunderstanding about any original claim or design specification–which assumes some level of cooling. Once you have inadequate cooling, forget it. With full meltdown the fuel forms a pool which heats even more than the pellets–because it is no longer moderated. It can never approach criticality–ie. like a nuclear bomb, but low level fission continues so it just keeps heating up. At a couple thousand degrees (if not before, remember there will be intense steam pressure by then, it is like a massive pressurized can) the steel will melt or soften enough for welds to give etc. By memory (dangerous but you can Wiki this) it can reach up to 5000 degrees so absolutely nothing can contain it.”

“Once all the SNF is fully covered again, the gammas will drop to virtually nothing.”

Can you, or someone else, provide a link to how simply covering nuclear fuel with water acts as a shield? I have known this works (it is what makes nuclear submarines possible), but I don’t understand the physics behind water stopping the radiation.

Geoff, I’m interested in the answer to “Michael R James”. My understanding was that the whole point of all the various containment infrastructure in a contemporary nuclear power plant was that it would contain a meltdown.

As Michael cites wikipedia, well wikipedia certainly seems to give me the same impression “In a modern reactor, a nuclear meltdown, whether partial or total, should be contained inside the reactor’s containment structure. ”

Were this not the case, and Michael’s comments were true, then I doubt there would be such a thing as a nuclear power industry.

In my opinion Unit 3 was already out of control after the explosion.
The pictures show a completely destroyed structure on this german page (http://www.spiegel.de/fotostrecke/fotostrecke-65742-2.html).
I can’t imagine, that anything is able to operate in there any more.
To my mind the PV in Unit3 was breached as soon as the white smoke began to rise.

I wonder about this due to the widespread confusion of “milli-” versus “micro-” Sieverts, but according to that article the legal upper limit of exposure for SDF personnel is 50 mSv, and the measured levels “greatly exceed” this upper limit at present (though specific numbers aren’t mentioned, nor is time, since actual dosage is time-dependent).

(The presence of steam clouds at a damaged BWR is a bit hard to explain otherwise.)

Also, do we have DATA (i.e. actual hard, scientific data, not TEPCO or GoJ claims) that refute the hypothesis of an unsuccessful SCRAM?

Because many have claimed that all reactors SCRAMmed successfully, but on digging I only got to statements by TEPCO which ultimately lead back to “they SCRAMmed because that’s how they are supposed to perform in such a situation”.

Which stands in stark contrast with the general reluctance of all other security measures that are more complicated than a simple chunk of dense matter to perform as they were supposed to be.

Thus, the most parsimonius starting hypothesis is: “the reactors did NOT SCRAM”. This hypothesis must be falsified by hard data.

Given the confidence with which 3+3 successful SCRAMs are proclaimed, I suppose there are some underlying hard data.
But given the general amount of entirely unscientific and purely faith-based reasoning by very many people claiming successful SCRAM, I would like to be sure.

So, is there anything in the isotope profile, thermal profile… that refutes this hypothesis conclusively? There should be. Physics is an exact science.

jacques “Can you confirm that Cesium and other radioactive elements with very long half lives were not released ?”

The vented radioactive gases are “mostly noble [chemically unreactive] gases, the majority of which had a half-life of seconds to minutes)” but what they decay to is mostly Strontium-90 (decay produce of Kr-90) and Caesium-137 (decay product of Xe-137), both biologically reactive multi-year half life substances. Omitting this is potentially deceptive.

My related concern is what else is in the vented steam/gases, with the fuel rods having been exposed for multiple hours – some decay products that were in the fuel rods will have migrated into the steam. Experts: What will this include ?

Does anyone know, or have qualified ideas about, the situation when it comes to restoring external power?
Are they working on this? It seems to me that if this had been done earlier, they wouldn’t be having all these problems now.
Or did the tsunami wipe out the so much of the electrical systems that this wouldn’t have helped (hard to believe this, since battery power kept things in check for quite awhile at 2-6).

Has the seawater (& explosions and fires) now damaged instrumentation and valves etc to such an extent that if reliable power to normal systems was restored now, we’d still have major problems?

Supposedly control room(s) had to be abandoned for the time being. Unclear if this refers to Daiichi-2 only, and if hot if the CRs of I-1, I-3 and I-4 are intact enough in the first place. Source: NHK.

(Note this seems to be a different event from the withdrawal of workers during the night. These workers are now on site again, but it is not clear how much of the reactor buildings is still accessible.)

Professor Brook, so are you going to delete the vicious personal attack on me by DV82XL? What a way to welcome a first-time poster!

Nobody who advocates a 2-year moratorium on the building of new nuclear capacity on the strength of nothing more than that one plant was compromised by one of the largest earthquake/tsunami cobinations in instrumental history is an advocate of nuclear power.

There can be no doubt that if there are lessons to be learned here (and I believe there are) they will be incorporated into new designs where salient.

@spangled drongo: Possibly, just as we largely ignored chernobyl as a data point for western reactors.

Seriously, what I newly learned here is that a reactors needs several *months* of care even after being shutdown in order to not starting to leak. I previously always assume that that would be on the order of hours to days. To deploy such systems in an region where war is remotely possible…urks.

Even more disilliosoning is that apparently even nuclear fuel stored without power for cooling has possibilities of becoming critical.

Besides, which (western) nuclear reactors haven’t killed anybody yet there remains the fact that we still have no clue how to deal with the waste. Germany has just one expermental final storage facility, which took in much more waste that it was supposed to (human greed factor) and also chemical waste. It is a former salt mine that was supposed to keep the waste dry for thousands of years, but in fact it is already drowning.

First reaction of the government was to free the plant owners whose stuff is in there from any further operative costs of that storage facility.

I think it *may* be possible to safely operate nuclear power stations from an engineering perspective, but am convinced that it is utterly irresponsible under any economic influence. And you can’t avoid that.

In fact, I would be quite happy if every NPP operator would just be required to take full insurance against any kind of accident, and the insurance would be required to prove that it doesn’t operate on an ‘go broke if something serious happens’ business model. That would pretty much take care of that.

How can this be INES-4? 30km/80km is a quite “creative” way to define “local”.

If I look at the INES criteria, this is level 5 to be sure:
* “Limited release of radioactive material likely to require implementation of some planned countermeasures.” – check.
* “Several deaths from radiation.” – pending (do the math for the emergency workers; a short-term dose of 8 Sv is generally considered point of no return).
* “Severe damage to reactor core.” – check.
* “Release of large quantities of radioactive material within an installation with a high probability of significant public exposure. This could arise from a major criticality accident or fire.” – check.

What some people here do not realize is how overwhelmingly the tide of public opinion has already turned against nuclear power. More than mere symbolic action will have to be taken by politicians to address this, otherwise Greens will be voted into parliamentary positions where they hold the balance of power.

During a two-year moratorium, a broad-based exploration and review of the overlooked risks in nuclear power can be done. Obviously not everywhere does a tsunami loom, but the loss of electrical power for cooling may be a design flaw that can happen elsewhere, too.

At the same time, more discussion of alternative designs such as pebble bed modular reactors or thorium reactors needs to take place. Why was research and development on these projects was curtailed? Was it lack of public funds due to lack of public interest?

A broad-based discussion could bring greater swaths of the public on board and rekindle development of safer alternatives.

To my mind one thing cannot be avoided. The Japanese should have known that Fukushima Dai-ichi was exposed to tsunamis. The Okushiri tsunami in 1993 was 30m high from 7.7 quake. The 83 quake was a 7.7 and generated a 10m wave. But still they did not protect the Fukushima electrical systems from a wave higher than 6m. It’s not a nuclear power technology failure I suppose but it was still stupid beyond belief.

Thank you for the precise exposition, I think it’s very important to avoid sensationalism like the media.
That said, if you read your first explanation you said the external containment was very solid and it was nearly impossible to breach, and that seems false at the moment (cit at the status graph of reactor 2 and 3).
Also, the problem with the spent fuel pool seems very serious to me, if the radioactivity is SO high nobody can go near it…
Hope I can get an explanation.

It’s the right decision under the circumstances. The silver lining in this crisis is that many millions of people have learned something about design and operation of nuclear power plants, whereas before it was all a mysterious “black box” to them.

“The Japanese should have known that Fukushima Dai-ichi was exposed to tsunamis.” – but they did.

If you understand what a tsunami is (hint: it is not a “flooding”, more like a marine transgression of limited temporal scope) you’ll understand why you can face it with little more than resignation, and by building as lightly as possible so that you can rebuild cheaply and the debris is less harmful.

Liquid water is not a compressible substance, and in this universe, momentum is conserved until it is bled off.

Basically highschool physics.

What they did instead is try and make their NPPs as earthquake-proof as they could with the technology available at the time of construction.

This is not some third-world low-tech failure. The tech that failed was about the best money could buy when it was built.

RE SCRAMming BTW – I noted that Japan has PWRs on the W coast almost exclusively, and only BWRs on the E coast. W coast is not generally hit by strong earthquakes. PWR SCRAMming while undergoing gravitational shock may be tricky; in any case I’d guess BWR SCRAMming would be more fail-safe (PWR releasing control rods at wrong time during quake will cause epic irrecoverable SCRAMming failure).

Is this the reason for the geographical distribution of PWRs vs BWRs in Japan? If not, what is it?

After reading through quite a few stories from yomiuri, nhk, kyodo etc… the situation as of now (10pm) from the Japanese media’s perspective is the unit is still undergoing emergency cooling with seawater, unit 2’s pressure suppression chamber may still be a source of leaking radiation, unit 3 although reports are not so clear they are attributing the white clouds (steam) to the spent fuel pool not the reactor… Hence why they are now (sometime tonight) going to pump water into the pool by the use of a high pressure water truck and us military pump trucks, this is the same for number fours spent fuel pool … Hopefully I translated everything correctly

I’m just waiting for the news to give some accurate dosage readings from after 4:00pm today… They haven’t published anything yet..

If anything else major pops up here (japan) I’ll try and summarize if no one else beats me to it

As Tokyo said, the amount of 1000mSv/h is HUGE. This is not something that is neglectable.
As American said, it is really absurd to write here “the situation is getting stable” (or similarily). We do not have any clear informations since days, and this is the best argument that things are completely out of control. If things were under control, Tepco and Japan would say that. They don’t. They keep information as far as they can away from us, so they won’t create panic in Tokyo and a deeper drop of the local stock market.

I expect some technical scenarios about worst-case. About best-case, you already advocated here enough, and the occurences of every following day have brought you more and more in abashment.

questions:
1) what are the connections to the outside (holes) in the concrete containment of the reactor? I see in the drawings of the M1 reactors two possible leaking orifices:
a) the upper lid of the containment (where the rods can normally be taken out to the pond)
b) different pipe lead-through openings in the containment.

as soon as the metal containments will/are broken, radioactivity came already out, between the metal and the concrete container.

2) what are the chances that the upper lid (the probably some 100 tons heavy one) can be blown away?

3) why are there so high amounts of radioactivity, if everything “is stabilising”???

I generally expect explanations of FACTS that happen, not theoretical small-talk about how things SHOULD be, but obviously are NOT.

You have here the chance to do it. Let’s see it.

Comment on the photo ( http://epcan.us/jlab-ep/s/ep88140.jpg ) :
The image of two of the reactors show dramatic damages, even at the level of the concrete structure, and not just a blow out of gases, as it was clearly seen some days ago. This cannot happen just because of a gas blow out, or just because a small fire (that extingushed itself later). This looks VERY serious.
And I am speaking as an architect.

The radionuclide traces mentioned formerly were found in the tap water of Fukushima City, CNN Mexico claims. (Their article is no good though. Original source of info is said to be prefectural nuclear authorities. I would very much like to see the original info.)

“Here are the facts about Tokyo Electric and the industry you haven’t heard on CNN:

The failure of emergency systems at Japan’s nuclear plants comes as no surprise to those of us who have worked in the field.

Nuclear plants the world over must be certified for what is called “SQ” or “Seismic Qualification.” That is, the owners swear that all components are designed for the maximum conceivable shaking event, be it from an earthquake or an exploding Christmas card from Al Qaeda.

The most inexpensive way to meet your SQ is to lie. The industry does it all the time.”

(…)

“In the US, we supposedly fixed our diesels after much complaining by the industry. But in Japan, no one tells Tokyo Electric to do anything the Emperor of Electricity doesn’t want to do.

I get lots of confidential notes from nuclear industry insiders. One engineer, a big name in the field, is especially concerned that Obama waved the come-hither check to Toshiba and Tokyo Electric to lure them to America. The US has a long history of whistleblowers willing to put themselves on the line to save the public. In our racketeering case in New York, the government only found out about the seismic test fraud because two courageous engineers, Gordon Dick and John Daly, gave our team the documentary evidence.

In Japan, it’s simply not done. The culture does not allow the salary-men, who work all their their lives for one company, to drop the dime.”

“Possibly, just as we largely ignored Chernobyl as a data point for western reactors.”

In fact Chernobyl is a central data point for western reactors. The accident is heavily studied by nuclear operators, because it was operator actions which caused the disaster; poor plant design only made it worse. The disaster is used to emphasize the importance of a deep understanding of how the plant works, the importance of following approved procedures, and the importance of keeping safety and automatic protective systems online. All of which were violated in the moments leading up to the Chernobyl disaster.

Nuclear power can be a very safe technology. As long as the industry continues to ask “how can it happen here” we will continue to improve our nuclear plant safety.

I’m surprised space or military technology doesn’t possess a suit that can block a good deal of the radiation for the workers…although looking at the Apollo suits, guess those wouldn’t be practical in Earth gravity….

Can anyone with more knowledge of the subject explain what would have happened to the three damaged reactors had no inadequate attempts been made to cool them with water? I imagine that, provided steam could be vented to prevent pressure build up, the cores would have dried, melted and been caught in the contained substructure where they would have eventually cooled. It had been my impression that this core catching role was the last line of defence. Is this perhaps not the case for reactors of this design? However, if it is, is it arguable that persistence in attempting to run with the penultimate level of defence in the absence of an adequate water supply has ,in fact, made matters worse and possibly compromised core catching possibilities in at least one of the reactors whose torus may have been cracked by hydrogen explosions?

Quite correct. To attenuate gamma rays, the suit would have to be made of an inch or two of lead and weigh tons.

Re DV82XL (16 March 2011, 12:51 PM): Perhaps my comment was sophomoric. However, I do not have to breath fumes from a poorly ventilated cooking fire in a poor part of the world that lacks electricity.

The consequence to the Japanese nuclear installations are tragic, and help to show that any fission technology, whether light-water, liquid sodium chloride-cooled, or a graphite block, cannot be operated without serious immediate risks, besides all the long-poisonous wastes left behind.

However, there are lots of ways to die, and the manners of life and death for poor people who do not get to benefit much from the technological innovations in rich countries, are generally much less pleasant than what Westerners are accustomed to.

“However, despite some earlier concerns, it is now clear that containment was not breached.”

citation, citation citation! Could you please clarify where that is taken from from?”

I agree this is a great site, but the damage assessment seems conflicting with official reports. Official reports admit that a breach of containment of reactors #2 and #3 is suspected. So it is not so clear after all that the containment is intact. Looks like spin to me.

Hopefully I can add a bit to 2 questions asked earlier in the comments

1. Can they blow a hole in the roof of 4 so they can drop water in?
A) if there is hydrogen built up in there that could be a disaster
B) the fuel rods in 4 are not contained. Any explosion could launch aerosolised and currently solid material into the atmosphere. Especially if a) is true

2. How good is shielding of personnel from radiation?
I am specialised in medical radiation. I agree that the suits will do nothing against gammas, but nothing wearable does.
My understanding was almost all decay in the uranium cycle alpha and beta decays though… so all the gammas come from beta decays, isomeric transitions and energy level changes? The suits, if proper decontamination is performed, should be pretty impregnable to alpha particles. The skin itself should be too! Just need to stop them swallowing any.
Maybe a nuclear physicist can explain what proportion of this radiation is alphas, because the workers are not at risk from that. Also correct me if I missed a source of gammas.

Eugene… when a Boeing 747 crashes many similar planes are taken out of service while investigations are performed. It does not signal the end of Aviation.

Mattb, exactly! Nor should Fukushima be taken as the death knell of nuclear power generation.

In a few months’ time, people will come around to a more dispassionate view of the risks and benefits of nuclear power. So, maybe the two years that I proposed initially for a moratorium on new construction is excessive.

I am open to persuasion on that, but I hope we can agree that policy makers will do well to be seen to take decisive action that will signal that the disturbing lessons from Fukushima will be taken fully into account, and not on a rushed schedule, either.

Largely reassuring, but I worry about sweeping statements such as this: “But even in the case of Chernobyl, the exclusion zone that they had was about 30 kilometres. And in that exclusion zone, outside that, there is no evidence whatsoever to indicate people had problems from the radiation. ”

These sorts of statements reduce the credibility of people downplaying the current crisis. I’m an economist and in my field, there is strong evidence that people far away were affected. E.g. http://www.nber.org/papers/w13347 published in the Quarterly Journal of Economics on effects in utero for Swedish children.

Prof. Brook, one thing is not clear to me…you mentioned that the cooling after insertion of rods happens exponentially and things should stabilise in a week or so. But you also state that the cooling ponds hold rods for years…

Would you mind clarifying if we are talking about two different levels of heat (cooled down in one case but hot enough for the next stage?)

To Johan at 17 Mar @ 12:29- Unfortunately, there is a potential for recriticality of the damaged core with reflooding, especially if the water is insufficiently borated. The control rods/blades would have melted and the geometry changed before the fuel started to fragment, with subsequent dispersal. No one knows the state of the core debris in any of the reactors at this point.

Mattb, read the earlier threads. _many_ plants ubuilt to this design are in service now. More recently built, more modern plants are still using the same batteries, fans, diesel engines, temperature and radiation sensors, wiring, and so forth. The whole range of failures here is going to need attention. The layout that lets radiation prevent operators from reaching the controls needs to be considered.

Mattb- I think that is partially reasonable logic. But one problem is that even this design of nuclear reactor was “supposed” to be immune to this type of disaster…so many failsafes were designed into the system, and at this point is unclear how many of them are properly working, but a lot have failed (if the containment vessel fails, that arguably suggests we have no idea how to contain a full meltdown…or at least when that meltdown is accompanies by tsunami triggered explosions accross the plant).

As of now, I think there is still some sense in which comparing this disaster to an airplane crash, re. the subsequent policy decision, makes sense. If there is significant release of radioactive Cesium and Iodine, that comparison no longer applies: accidents in planes don’t wipe out >30 square miles of the environment.

Hank for sure… I was more referring to a moratorium on new plants… the thing that irks me at the moment is that these spent fuel pools, well I know there was a lot to worry about elsewhere in the plant but it would not have been hard to keep tabs on those pools and top up the water before things got to this stage. Seems quite unneccesary… although I do acknowledge they were slightly preoccupied!

Current developments have set back the Gen III cause, but this incident could actually be a real kick start for Gen IV as so much risk can be avoided. COuld it be sold to people as something they could tangibly identify as being different to what the currently understand as nuclear.

Even more so the cause of the Thorium reactors as the lack of Uranium in the name will get people interested.

Mattb, read the earlier threads. _many_ plants ubuilt to this design are in service now.

I think the key problems in “this design” as in the GE “Mark I containment” that probably had impact to the severity of this accident, are the size of primary containment (larger more modern primary containment has a much larger volume and such a higher pressure marging in core cooling failure or fuel melting situations) and the location of the spent fuel pool outside of primary containment but in a high elevation location next to light construction roof and walls susceptible to hydrogen explosion damage.

In other words, passive design features where safety margings would come to play only when all of the active measures have already completely failed, as in this “above design basis accident”.

Last comment from me tonight will leave to the brains trust from here… but having followed the BNC debates since pretty much day 1 I think that one thing this incident does is totally remove the possibility of toning down some of the safety factors that make nuclear reactors expensive and slightly uncompetitive. I can’t see any regulatory authority toning things down for many a year.

Good news for a change, TEPCO is preparing to connect external grid power to reactor 3 per NEI:

Restoration of electrical power to the site was under way at the Daiichi plant as of 6:00 a.m. EDT Wednesday. A temporary cable was being connected between an off-site power line and Daiichi reactor 3. Off-site power has not been available at the site since the earthquake on March 11.

These seem more informative than anything I’ve found to read. Every reporter is saying the company and government aren’t saying anything and seem confused. Reuters has experts on live who don’t even know which plant has six and which has four reactors or which ones are in cold shutdown.

It reminds me of something I learned long ago about Microsoft Word that may be true of industrial civilization in general — it’s capable of building a very large, complicated document — a much larger and more complicated structure than it can continue thereafter to revise and maintain without it eventually crashing. Eventually one little thing goes wrong, and that leads to two, and those lead to four.

The U.S. military will operate a Global Hawk unmanned high-altitude reconnaissance aircraft over a stricken nuclear power plant in Fukushima Prefecture, possibly on Thursday, to take a closer look at its troubled reactors, a Japanese government source said Wednesday.

Photographs taken by the plane equipped with infrared sensors could provide a useful clue to what is occurring inside the reactor buildings, around which high-level radiation has been detected.

First wanted to thank Barry and most of the posters here for the excellent work. I’ve gotten far more insight here then all my other sources combined.

Secondly, as an engineer, my impression is that the the focus of designing reactors is on the reactor itself and not enough hardening is done for the external generators and storage facilities.
If the external generators had been in a hardened facility a lot of these problems would never have occurred.

Germans have been attempting to plot and correlate the publicly released radiation measurements against timed reports of various explosions and venting events. Comparisons between earlier days and the situation today is being hindered by unability to get measurements from the closest measurement posts (or locations for the mobile measurement vehicle to stop at), because the dose rates are too high to keep up continued manual dose rate counting.

If the graph is accurate, it does show a very disturbing trend indeed.

1. How are they injecting the saltwater? Are they putting it in the circulatory system and pumping it through or somehow directly into the pressure vessel.

If the first case they would be trying to use the heat exchangers to remove heat, but these are designed for deionised water, not boiling hot seawater as are the pumps. The corrosion would be great and they would both probably fail. Also they would collect incredible radiation levels and would be unapproachable for removal or repair.

If the second case then the only way to remove heat would be to literally blow off steam with all the radiation release that implies.

2. Some or many fuel rods have been damaged. The zirconium has reacted with the water to produce hydrogen. The heat stress of this exothermic reaction may have cracked some of the uranium pellets. They must have many stress fractures from just being in the reactor under normal operation. Now you bring hot corrosive sea water in contact with these pellets. I can’t imagine a better leaching agent (ok maybe I can, but you get my point). This seems likely to mobilize a good fraction of the fission products (any thing over a few tenths of a percent is a huge amount of radioactivity). Is this likely or are the pellets strong enough to resist this?

3. I still can’t understand how 5 m of water evaporated from the top of the spent fuel pond. The newest spent fuel rods were taken out months ago (November, I believe). How is there enough residual heat to evaporate that much water? Is it possible that the pond cracked and slowly leaked out water? From the physics, this seems much more likely to me.

I’d like to revise my third question. The leak could be from craked pipes or pumps in the cooling system for the spent fuel pond. Maybe not noticed in all that was going on until too late, but this is still speculation. The evaporation just doesn’t seem physically possible.

Hello, I live in Tokyo, around 250kms away from Fukushima. The discussion here is all very fascinating, but I would like to ask your opinion on how dangerous it is to stay here. I understand the worst-case scenario for me would be a fire or explosion exposing the rods, releasing a large amount of radioactive particles into the air, and a wind carrying those particles to Tokyo. If this happens, what is the probable level of hazard to my health?

The leak could be from craked pipes or pumps in the cooling system for the spent fuel pond. Maybe not noticed in all that was going on until too late, but this is still speculation. The evaporation just doesn’t seem physically possible.

The only drains and inlets are very high in the pool wall just to prevent the possibility of a pipe leak from draining the pool. One estimate for evaporation rate for a couple months ago changed 1/3 of 150 tons of fuel was about 10 m^3 per hour (about 2,900 galons). Reactor 4 had all of its core unloaded to the spent fuel pool in November 30th 2010. I think the pool size is something like 1,500 m^3, so a Stetson estimate for the less problematic pools would show that they could take as long as a week to reach boiling temperatures, while the pool at reactor 4 could be running almost dry 5 days after shutdown of its cooling.

Proper estimates would require very detailed knowledge of the fuel configurations and also about the current state of the pools under damaged or destroyed roofs.

this may be a stupid suggestion, but hearing about all this sea water issue, got me thinking re the problems getting it to where they need it most, can all you more scientific brains out there, think of any other substance they could used e.g. a varity of ice that would melt to water, or other cooling agents or somthing that would chemically do the same job or mop up or ingest or make inert the problem substances?

When the reactors SCRAMed on 11 March after the earthquake, and went sub-critical, their power levels dropped by about 95 % of peak output (the nuclear fission process was no longer self-sustaining). Over the past 5 days, the energy in the fuel rods dropped by another ~97 % …

The crude tool available to me — the Untermeyer and Weill rule — gives the below numbers. They are fractions of the power up to the moment of the earthquake, supposing that to have been constant for 1 year (although an assumed run time of six months would yield almost exactly the same).

0.0159 at 1 hour (about when the tsunami hit)

0.0083 at 12 hours

0.0067 at 24 hours

0.0054 at 48 hours

0.0047 at three days

0.0042 at four days

0.0039 at five days

Five days is about where we are now, so I get that 94 percent of the radioactivity that existed at the moment of shutdown, in agreement with “~97”.

As an ancillary question, is it fair to assume that the Fukushima plant will not be recommissioned, and if that is indeed true, what would the medium term impact on the population in terms of loss of power-generating capacity?

“a Stetson estimate for the less problematic pools would show that they could take as long as a week to reach boiling temperatures, while the pool at reactor 4 could be running almost dry 5 days after shutdown of its cooling.”

Then it looks like they are going to have to design passive convection cooling into future spent fuel pools. I think this shows a problem in nuclear accident probability calculations. Any one of these failures have a very low probability. If you multiplied them out, you would figure the world would end first. But all of them are caused by a single source. They are not independent probabilities. And then the diasater around the plant limits outside help. Radiation levels rise and you have to get rid of most of your personnel. You start injecting seawater which I doubt has ever been modeled and you are in a very uncertain situation. Reminds me of the Space Shuttle and reliability estimates that would never have predicted a loss of 40% of the fleet. This accident will have to be very carefully analysed before anyone can say what the future of nuclear power will be. It will not save the planet from Global warming as under even the most optimistic projections it will only satisfy a small part of our energy needs. It could be a part of the solution, but only a small part so it is not really an argument for or against nuclear power. Delaying carbon dioxide levels by a few years is not a solution.

Then it looks like they are going to have to design passive convection cooling into future spent fuel pools.

I was under the impression that this was the initial design for many BWRs, while PWRs used borated water in the pools. In any case, the stacking of very high densities of spent fuel in the cooling pools and keeping them there for years is a relatively new development.

Not all regulatory authorities in different countries have agreed that so high cooling pond densities are desirable and for example in Germany they have a tendency to quickly move spent fuel to dry storage after the initial high decay cooling, which is done at such low density convective cooling should suffice.

It could be a big cost issue to require less dense first stage cooling pond packing, if the other spent fuel processing is seriously backed up and no final storage available. I believe Germany is much further in the spent fuel storage “pipeline” so to speak, or in other words they don’t rely keeping spent fuel in as high total masses and for as long at their plant sites as opposed to for example US and Japan.

“This figure illustrates the current reported state of the Daiichi and Daini reactors, last updated 1230 on 16 March (click to enlarge)”

Hello Barry, when you get a chance you could update the chart to the new one from 1900. Some changes like the possibility that the white steam from reactor 3 is cause by the SPF and not by damage of the containment and lower radiation readings. Thank you.

New update from The Federation of Electric Power Companies of Japan (FEPC) Washington D.C. Office

As of 10:15AM (EST), March 16, 2011:

* Radiation Levels
o At 6:40AM (JST) on March 16, a radiation level of 400 milli sievert per hour was recorded outside the west side of the secondary containment building of the Unit 3 reactor at Fukushima Daiichi Nuclear Power Station.
+ At 6:40AM on March 16, a radiation level of 100 milli sievert per hour was recorded outside the west side of the secondary containment building of the Unit 4 reactor at Fukushima Daiichi Nuclear Power Station.
o At 8:47AM on March 16, a radiation level of 150 milli sievert per hour was recorded outside the secondary containment building of Unit 2 reactor of Fukushima Daiichi Nuclear Power Station.
+ At 8:47AM on March 16, a radiation level of 300 milli sievert per hour was recorded between the exteriors of the secondary containment buildings of Unit 2 reactor and Unit 3 reactor of Fukushima Daiichi Nuclear Power Station.
+ At 8:47AM on March 16, a radiation level of 400 milli sievert per hour was recorded outside the secondary containment building of Unit 3 reactor of Fukushima Daiichi Nuclear Power Station.
+ At 8:47AM on March 16, radiation level of 100 milli sievert per hour was recorded outside the secondary containment building of Unit 4 reactor of Fukushima Daiichi Nuclear Power Station.
o At 10:40AM on March 16, a radiation level of 10 milli sievert per hour was recorded at the main gate of the Fukushima Daiichi Nuclear Power Station.
o At 4:10PM on March 16, a radiation level of 1530 micro sievert per hour was recorded at the main gate of the Fukushima Daiichi Nuclear Power Station.
o For comparison, a human receives 2400 micro sievert per year from natural radiation in the form of sunlight, radon, and other sources. One chest CT scan generates 6900 micro sievert per scan.
* Fukushima Daiichi Unit 1 reactor
o At 6:55AM on March 16, the pressure inside the reactor core was measured at 0.17 MPa. The water level inside the reactor core was measured at 1.8 meters below the top of the fuel rods.
* Fukushima Daiichi Unit 2 reactor
o At 6:55 AM on March 16, the pressure inside the reactor core was measured at 0.043 MPa. The water level inside the reactor core was measured at 1.4 meters below the top of the fuel rods.
* Fukushima Daiichi Unit 3 reactor
o At 8:37AM on March 16, white smoke was observed emanating from the vicinity of the secondary containment building.
o At 9:55AM on March 16, the pressure inside the reactor core was measured at 0.088 MPa. The water level inside the reactor core was measured at 1.9 meters below the top of the fuel rods.
o At 11:32AM on March 16, it was determined that the possibility of significant damage to the primary containment vessel was low.
* Fukushima Daiichi Unit 4 reactor
o At 4:08 on March 15, the temperature of the spent fuel pool was measured at 183 degrees Fahrenheit.
o At 5:45AM on March 16, a fire occurred in the vicinity of the third floor of the secondary containment building.
o At 7:26AM on March 16, no flames or smoke was observed and thus it was concluded that the fire extinguished on its own accord.
* Rokkasho Reprocessing Plant and Accompanying Facilities
o From 12:00PM on March 15, power generation from the commercial electricity grid was restored for all facilities. It was confirmed that no fire, damage to equipment, injuries to personnel occurred. Radiation levels were measured at a normal level of safety.

Hank Roberts, on 17 March 2011 at 4:44 AM said:
“Gentlemen, you shouldn’t argue politics here.
This is the war room.”

Sorry, I am not anti-nuke, but believe all information is important in making decisions. But that is for somewhere else. I thought the Global warming comments were somewhat relavant given the purpose of this website, but again in another forum.

Hydrogen from No. 4 could only come from hot zirconium (overheating of the spent fuel pool). Spent fuel pool in No. 4 does not contain spent fuel. It contains all of the rods from the No.4 reactor (no spent) that had been removed for shroud maintenance. There is a “non-zero probability” (possibility) of reaching critical and therefore fission outside of containment. Recent comments of the NRC Chairman to congress would seem to indicate that the guesses given by Laurence Williams, professor of nuclear safety at the University of Central Lancashire, are spot on: http://www.bbc.co.uk/news/science-environment-12762608

From the BBC web site.
Anyone in the US have any information on the credibility of Jaczko’s alarming statements?

1837 GMT: Gregory Jaczko, head of the US Nuclear Regulatory Commission (NRC) has said there is no water left in the spent fuel pool in reactor four, adding: “We believe that radiation levels are extremely high.” Mr Jaczko was speaking to Congress in Washington and it was not immediately clear where his information had come from.

Would it be true to say that if it runs dry, the whole thing will heat up and give out a lot of local radioactivity (which would stay local)? In this case, would dousing the whole thing with boric acid (when this is possible) get things back under control without explosions and other things that might spread the radioactivity?

things are all but “clearly (slowly) stabilising” as stated in this blog post. See what another specialist says on CNN:

Dr. Helfand said reports suggested that the operation was not going 100% to plan, describing it as “something out of an adventure movie.”

“We are in totally uncharted waters, people are ad-libbing to deal with the situation,” he said. “Using fire trucks to pump a mixture of sea water and boron onto the reactors is not in any of the manuals.”

“These workers are trained to understand the risks, but that only makes it all the more heroic that they have agreed to stay and work to prevent a disaster,” he said.

“They know that if there is a reactor meltdown it could be a major disaster affecting huge areas and massive numbers of people, and they are risking their lives to try and prevent that. All of us owe them a huge debt of gratitude.”

btw, anyone have any information on my other questions above about how they are injecting water and the integrity of the uranium oxide pellets?

The question about the integrity of the UO2 or UO2/PuO2 pellets is probably impossible to answer since direct measurements of their temperature is unavailable.

However, they don’t have to break to release a significant amount of decay products, since these are held between the pellets and the zircaloy tube, so only the melting or cracking of zircaloy is necessary for their release. I believe they are issuing the estimates for 33-70 % of rod damage for the individual reactors by measuring Cs137 and I-131 concentrations from the reactor coolant samples. The separate question about what effect seawater has on already damaged rods is probably not that well studied or understood. It can’t be good for long term, but in short term it’s probably better to cool them with seawater than nothing!

With regard to the water injection, I’ve seen reports of at least 6 different attempted or considered ways to get water in to the PRVs and primary containment
1) using the plant diesel fire pumps and firefighting lines connected directly to a suitable PRV inlet
2) large capacity pump trucks with pipe connections to plant piping
3) ordinary fire trucks with their integral pumps and own hoses
4) police riot control “fire cannon” trucks with steerable high pressure pumps allowing long range spray
5) ARFF vehicles (similar pump and spray nozzle arrangement but higher pump capacities than the police vehicles)
6) airdrop by helicopter

I believe methods 1-3 and 6 have been attempted with varying success, with 4 and 5 approaching the more desperate end of possibilities.

Mike, on 17 March 2011 at 5:04 AM said:
Fukushima-shi (~65 km away): 21.4 uSv/hour at midnight on the morning of the 17th.
Kita Ibaraki-shi (~70 km away): 15.8 uSv/hour at 11:40 pm on the 16th.

As a comparison the average world background as listed by Wikipedia is 2.4 millisievert (mSv) per year.

Or given 24×365.2425 = 8765.82 hrs per year

So average background is

2400 uSv/8765.82hrs = 0.27 uSv/hour

So the above radiation levels are 79 and 58 times world average background respectively. Of course background radiation varies dramatically world wide and natural background exceeds these levels in some parts of Iran.

“So the above radiation levels are 79 and 58 times world average background respectively.” vs. “The article above notes that this amount is a small fraction (1/30 to 1/40) of the dose one receives from a medical x-ray, it doesn’t take that many hours to start accumulating a non-trivial dose.”

What does this really mean, e.g. if the situation continues with these kind of radiation levels or slightly lower or higher in the next few days and weeks? Acceptable? A danger for humans, animals etc? Is it safe for the people to go outside again in the 30 km or even 60-70 km radius for hours per day?

And what does it mean for the up to 30 km of land around the plant? Can it be repopulated later or used as farmland etc – assuming things will stabilize as expected?

Luke Weston, on 17 March 2011 at 5:15 AM said:
“William, seawater and freshwater is being injected into the drywell – into the primary containment vessel – through a fire extinguishing line.”

OK, thanks. So that is beween the concrete walls of the reactor and steel pressure vessel with the fuel inside? That has not been clearly reported anywhere that I’ve read. I must say that is a relief. So is there any passive or active circulation going on in the primary heat transport system? Otherwise conduction is not nerely as efficient at getting the heat out of the
core. I guess that reduces my concerns for my third question above as I assume this situation has at least been modeled for a partial core “melt”.

William Fairholm wrote,
“So the above radiation levels are 79 and 58 times world average background respectively. Of course background radiation varies dramatically world wide and natural background exceeds these levels in some parts of Iran.”

Indeed, the article I linked says those measurements are ~530 times and ~300 times normal, respectively. I’m not sure what to make of those numbers, as they are an order of magnitude greater than your calculations. I do not know what normal background levels in Japan are.

OK, I just read the JAIF latest pdf. It says they are injecting seawater to both the core and the containment vessel. Sounds like this contradicts Luke Westons statement above, unless I am misinterpreting this.

What does this really mean, e.g. if the situation continues with these kind of radiation levels or slightly lower or higher in the next few days and weeks? Acceptable? A danger for humans, animals etc

Natural background radiation varies by a factor greater than 100, so 100 x natural average is not really “danger for humans or animals”. However, the protection limits for doses are in many countries quite low compared to the variation of background radiation, since they are based on excess of local average. These limits provide a very large buffer between radiation doses that can be scientifically proven to be hazardous and those that will result in evacuations and restrictions for usage of farmland and agricultural products.

For example, the often used protection limit that requires staying inside (so called “protection in place”, which is supposed to happen in a sudden emergency during the worst fallout and precede evacuation, if there has not been sufficient time to arrange evacuation before the arrival of fallout, as there has been in Japan) is 100 uSv/h, microsieverts per hour.

You could stay outside indefinitely without developing radiation poisoning and work outside (assuming 8 hours per day 5 days a week) for over three months before any detectable increase of cancer risk. Incidentally, the protection level of 100 uSv/h is still only three times the highest measured natural backround radiation level in Ramsar, Iran.

I think everyone with questions on radiation, stop and spend some time with Wikipedia learning the basics.

Prompt radiation in in the form of gamma, or fast heavy particles, is only an danger to living tissue if this tissue is directly exposed. Like a light source, once it is turned off the danger is over. While there can be secondary activation of some elements from this type of radiation that will make them radioactive, this occurs at many more times the radiative flux that we are seeing here.

Radioactive isotopes, as as by-product of a nuclear reaction, can continue to radiate for various periods after the initial reaction has finished. Spread about as a particulate, or dissolved in water, these may contaminate an area rendering it unsafe to a greater, or lesser degree. However very little of this type of fission product has been detected entering the environment due to this incident to date.

It is important not to confound these two different concepts, they are two very different things. It would seem though that many here, and many of the news outlets are confused.

“Indeed, the article I linked says those measurements are ~530 times and ~300 times normal, respectively. I’m not sure what to make of those numbers, as they are an order of magnitude greater than your calculations. I do not know what normal background levels in Japan are.”

I would think sealevel to reduce cosmic rays and no granite around might make another 3 or 4 difference in levels, so don’t really know and not that important.

Eagles Eyes wrote,
“What does this really mean, e.g. if the situation continues with these kind of radiation levels or slightly lower or higher in the next few days and weeks? Acceptable? A danger for humans, animals etc? Is it safe for the people to go outside again in the 30 km or even 60-70 km radius for hours per day?”

Well, I would personally want to limit my own dose from contamination, my occupation, etc. to 50 mSv (less if at all possible) over the course of my lifetime.

At about 10 uSv/hour, I would accumulate a dose of roughly 250 uSv/day of exposure, or 0.25 mSv/day of exposure from the contamination. Assuming I went outside for four hours per day and received no additional exposure inside, I would hit my 50 mSv personal lifetime comfort limit in a little over two years (roughly 800 days).

“And what does it mean for the up to 30 km of land around the plant? Can it be repopulated later or used as farmland etc – assuming things will stabilize as expected?”

Couldn’t tell you, unfortunately. That depends on the nature and extent of the contamination. Cs-137 has a half-life of around 30 years, if I remember correctly, but I don’t know much about the phytoaccumulation of Cs (save that it behaves similarly to K, and perhaps also to ammonium) so I’m unsure.

Other contaminants/degradation products, I have no clue. One would expect that particulates would be chiefly distributed closer to the Fukushima Daiichi site, though, so it’s reasonable to expect some contamination of soil, water, etc. (to an unknown extent at this point). I don’t think there’s that much data on exactly what to expect, though there are places to start–I think phytoaccumulation has been studied at the Hanford Site in the US, for example. That would at least give some indication of the safety of food crops grown in the region.

Also, though I’ve never personally been to Fukushima, I’m reasonably certain it’s like most of the rest of rural Japan–it’s already used for agriculture. What the consequences of this event will be for regional agriculture remains to be seen.

OK, I just read the JAIF latest pdf. It says they are injecting seawater to both the core and the containment vessel. Sounds like this contradicts Luke Westons statement above, unless I am misinterpreting this.

They started with injecting fresh water to the cores and seawater to containment, but when fresh water ran out, they switched to seawater for core injection also. It’s probable that they have exhausted all fresh water reserves by now and only seawater remains available.

Umm sorry, apparently I can’t do algebra. I think my post above should say 1200 days, not 800 days (since 4 hours per day outside would get me a 40 uSv or 0.04 mSv dose). So about 3.5 years to get to 50 mSv.

For those looking at radiation levels, I have heard that staying indoors will reduce exposure by a factor of 10, which is why they are telling people to do so. They still haven’t told anyone to take potassium iodide that I have heard (maybe a few directly contaminated and the workers of course.)

“Meanwhile, the science and technology ministry said the radiation level in Namie, Fukushima Prefecture on Tuesday was around 6,600 times higher than normal. The town lies within the area where residents have been urged to stay indoors.”

I’m still trying to work through the conflicting reports, but I believe that the fuel pond at #3 reactor is the source of yesterday’s “billowing white smoke” which was revealed by an NHK helicopter 30 km away, not by “Official” sources. So it’s radioactive steam and I think there are now *at least* two sets of rods which are directly exposed to the atmosphere.

DV82XL wrote,
“Prompt radiation in in the form of gamma, or fast heavy particles, is only an danger to living tissue if this tissue is directly exposed. Like a light source, once it is turned off the danger is over.”

I’m not positive, but I think you may be mixing up your Greek alphabet. Gamma rays are extremely high-energy (more so than x-rays) and very penetrating.

For comparison, ~25keV x-rays are penetrating enough to get through an inch of silicate (e.g., glass). Gamma rays have energies of 100keV+, so they are quite penetrating (and quite damaging).

For some perspective on radiation: Pocos de Caldas, in Brazil, has background levels of radiation, just due to radio-isotopes in the ground, of over 7 rem/year.

Some areas in Iran are getting up to 26 rem/year which is considerably bigger than the exposure from the Fukushima Daiichi plants. It appears they do not have more cancer and in fact have fewer chromosomic abberations. Speculation is that prolonged exposure is good, acute high dose is bad, though there is no evidence for this speculation. Certainly the linear no threshold model is very wrong. Check it out, a nice read:

Mike, gamma rays are in fact so penetrating, that most of them actually go through the body – they don’t attenuate. Also gamma ray is whole body radiation.

The real scary stuff is short to medium lived bio-accumulating alpha emitters. So far these have been measured as minute. Hard core blowout is required to emit these into the environment, but this is impossible at this point: the decay heat is only 0.2 percent of full power right now, not enough driving force to do a Chernobyl.

Chernobyl was a runaway reactor with positive void coefficients that created 10000% full power output. Fifty THOUSAND times the Fukushima driving force right now. Plus the Chernobyl plant had poor primary containment and burning graphite. Fukushima reactors have neither.

Despite the confusing media circus with journalists that don’t know the difference between a fission product and a transuranium element, things are looking pretty ok right now in terms of public safety and risk of large contamination of nearby land.

“Inhabitants of Ramsar have lived for many generations in these high background areas…This suggests that adaptive response might be induced by chronic exposure to natural background radiation as opposed to acute exposure to higher (tens of mGy) levels of radiation in the laboratory.”

I’m interested in reading this, but already my question is, what good is evolved resistance to high levels of natural background to people who haven’t evolved it?

Cyril R. wrote,
“The real scary stuff is short to medium lived bio-accumulating alpha emitters. So far these have been measured as minute.”

Fair enough, I know I personally don’t want alpha-emitters in my lungs, for example…And the workers are wearing breathing apparatus and are fully covered, so presumably some of that risk is reduced.

However, I would point out that it seems that high levels of gamma (and other) radiation might be important for the immediate situation at the site itself. That’s perhaps the only reason we got started on gamma rays in the first place, I think.

Gregory B. Jacz, chairman of the Nuclear Regulatory Commission, told a congressional subcommittee Wednesday that the secondary containment system of reactor No. 4, which was shut down at the time of the quake, was apparently destroyed due to a hydrogen explosion in the unit.

“There is no water in the fuel pool, and we believe that radiation levels are extremely high,” he testified.

He added that there is also the possibility of a crack in the spent fuel pool in reactor three “which could lead to a lost of water in that pool.”

White steam-like clouds drifted up from the reactor complex which, the government said, likely emitted a burst of radiation that led to the workers’ temporary withdrawal Wednesday.

Cyril R says:
“Despite the confusing media circus with journalists that don’t know the difference between a fission product and a transuranium element, things are looking pretty ok right now in terms of public safety and risk of large contamination of nearby land.”
Nice call. That is probably why the NRC just gave such an upbeat assessment of the situation.

Just wanted to point out again that according to the latest JAIF update posted here by William Fairholm containment integrity for reactors #2 and 3 is: “damage suspected”. So it is not so “clear” that containment was not beached. Keep up the great work guys.

Barry, confirming what em1ss wrote just above, we had mention of the crack reported yesterday. E.g.:

Japan safety agency: roof cracked at Fukushima No 4 reactor Tue Mar 15, 2011 8:46pm GMT
TOKYO, March 16 (Reuters) … after Tuesday’s explosion at … the No.4 … Agency official also told a news conference there was a crack in the roof of the reactor building….

More on that “US nuclear chair” – who has now been named as Gregory Jaczko, the chief of the US Nuclear Regulatory Commission, currently giving a report to Congress.

He says all the water has gone from the spent fuel pools at reactor No.4 in Fukushima No.1 facility, Japan’s most troubled nuclear plant. This means there is nothing to stop the fuel rods from getting hotter and ultimately melting down.

The outer shell of the rods could also ignite, with enough force to propel the radioactive fuel inside over a wide area, he says.

Gregory Jaczko did not say how the information was obtained, but the NRC and US Department of Energy both have staff on site at the Fukushima complex of six reactors.

He says officials believe radiation levels are extremely high, and that could affect workers’ ability to stop temperatures from escalating.

William, salt water is better than no water period…. Once it’s used the unit is likely defunct, but it’s safer for the public exposure… Do you really care about the ability to restart a unit when you decide to inject sea water, no…. You do that to protect the public and limit the release….

Mr.Brook, thank you for updating the Nuclear Accident in English forpeople in the world. As Japanese, even I understand Fukushima won’t be like Chernobyl disaster, I am so afraid to have my family in North East Japan, and don’t know what to do since Japanese government only say ‘We are dealing with these problem right now’ every time I saw the TV…:( Hope everything gets better soon…

Been following these posts for a couple of days. Love the objective “fact” based mentality and the civil attitudes around here. Thank you Barry and anyone else contributing useful information as best as practical.

“Also, though I’ve never personally been to Fukushima, I’m reasonably certain it’s like most of the rest of rural Japan–it’s already used for agriculture.”

Google Earth has been there.

It’s hard to estimate exactly, but as usual in Japan all relatively level ground is used for settlements and/or agriculture. The nonlevel ground comes in complex shapes; I’d presume that about 50-60% of all non-built-up ground within 10 km of Daiichi is used for agriculture.

Glad for the new reference, em1ss, it’s so hard to know what’s going on that even if it’s the same news item coming ’round the world from the other direction, it helps to know what the guy noticed and cared to announce. Does it sound to you like the new report you passed on is more than an echo — like he has newer info about the crack and what’s happened?

Yup. I can’t blame the reporters –they are saying the same thing about the sparse and contradictory information they’re being given by the company and the government.

I wish the editors were making sure to have timestamps and sources on every piece they release or put online, though.

Weird how things show up in Google (have we said thankyou to Google recently? and the SPOT satellite corp?). Like this image and story — first Google news hit at the moment and it’s from the Sofia news agency:

“… A handout image made available 16 March 2011 by Japanese Fukushima nuclear plant operator Tokyo Electric Power Co (TEPCO), showing the destruction and white smoke from reactor block 3 (3-L) and remains of reactor block number 4 (R). EPA/BGNES

Japan’s nuclear crisis in the Fukushima nuclear power plant as a result of Friday’s earthquake has shown signs of worsening amidst international warnings that the radiation levels on the spot are on the rise.

Yukiya Amano, the head of the International Atomic Energy Agency, characterized the situation at the plant as “very serious,” and said he planned to fly to Japan from Vienna, according to reports. The emergency situation in Japan has worsened amidst growing radiation concerns.

Speaking at a US House of Representatives Energy and Commerce subcommittee hearing, Gregory Jaczko, head of the US Nuclear Regulation Commission, warned that radiation levels around Japan’s troubled nuclear power plant may give emergency workers “lethal doses” of radiation, preventing them from getting near the plant.

“We believe that around the reactor site there are high levels of radiation. It would be very difficult for emergency workers to get near the reactors. The doses they could experience would potentially be lethal doses in a very short period of time,” Jaczko said, as cited by BGNES, while also noting that the US regular had limited information of the situation on the ground.

Testifying in Congress earlier, US Energy Secretary Steven Chu said the United States believes a “partial meltdown” took place at the plant, but he also said he did not want to speculate about events there.

“The site is effectively out of control. In coming hours there could be further catastrophic events which could pose a threat to the lives of people on the island,” Energy Commissioner Guenther Oettinger told a European Parliament committee.”

The picture linked above from the Sofia news site in Bulgaria — anyone seen where it first was given out? It”s not linked at the TEPCO website, so no idea when it was taken or if there were other pictures or explanations released at the same time.

Regarding the spent fuel rod failures, it sounds scary but you have to take into account three mitigating factors.

The fuel is considerably older than the reactor fuel (months). This means:

1. Less heat. You need only a garden hose to keep it filled. But what if they can’t fill it? Consider the following:

2 No dangerous shortlived iodine and many other bio-accumulating dangerous fission products. The primary release will be of fission gasses which are noble chemically, won’t get into the body, immediately flow upward and diffuse. This harms no one – unless you’re a helicopter flying right over the spent fuel pool (!)

3. The non volatile fission products and plutonium will stay in the fuel rods because they won’t boil away. Very different from Chernobyl where there was a hundred thousand times more driving force plus a nasty extremely hot graphite fire to make things worse.

4. The fuel rods are individually very small; depending on reactor size there are between 30,000 and 80,000 fuel rods in a full core loading so individual failures are quite limited in radiological release.

Don’t get me wrong – I wouldn’t want to be standing next to those pools right now! But as always its important to consider the real risk to the public and put the risk in perspective, media exaggerating and comparisons with Chernobyl are not helpful.

Just read unconfirmed “leak” info, that reactors are under control now, pools for spent fuel are the only problems now (not small mind you). Hopefully this info is correct. It comes from non-Japan source.

In one of the TV interviews with a government minister, I am pretty sure he said that fresh fuel was in the rooftop holding pond for Unit 4, waiting to be loaded into the reactor. I don’t have a link or cite and don’t know that’s accurate — it would be newer information than the inventory numbers from last fall, if so.

Jaczko, current NRC chairman, is reported by the NYTimes to have said in Congressional testimony “that the commission believed that all the water in the spent fuel pool at the No. 4 reactor of the Fukushima Daiichi Nuclear Power Station had boiled dry”. “We believe that radiation levels are extremely high, which could possibly impact the ability to take corrective measures”. The NYTimes report stated that “it is possible the authorities there” [ in Japan ] disagree with Mr. Jascko’s conclusion about the exposure of the spent fuel, or that they have chosen not to discuss the matter for fear of panicking people”

Panic is not something the NYTimes fears to foment.

Meanwhile over at The Energy Collective, there is a “Statement from All of Us at Social Media Today, Hosts of The Energy Collective” which emphasizes that just because The Energy Collective published the Dr. Oehmen post, which “has become the most heavily trafficked post in the history of The Energy Collective” it does “not mean that we endorsed or refuted his relatively optimistic take on the Fukushima disaster”

Its now getting controversial to have an optimistic take on what’s happening. They are also at this moment delaying posting the optimistic remarks of Ted Rockwell, the Technical Director of the program that built the world’s first commercial nuclear reactor, i.e. Shippingport.

em1ss, on 17 March 2011 at 7:13 AM said:
“William, salt water is better than no water period…. Once it’s used the unit is likely defunct, but it’s safer for the public exposure… Do you really care about the ability to restart a unit when you decide to inject sea water, no…. You do that to protect the public and limit the release….”

Oh that is not my concern. Even before injection of salt water these reactors were not going to be restarted, just as Three Mile Island was not. It is what hot corrosive salt water is doing to the to the pressure vessel, valves and fuel cladding that is my concern. These systems were designed for pure water (ok, LiOH for ph control to reduce corrosion and Hydrogen to suppress radiolytic oxygen formation), but essentially pure for this discussion. As they blow off steam the salt concentration must be increasing. I have no idea what this is doing, but it is not good. It has never been modeled. Unless you know of someone who has done this. That is my concern.

The total number of fuel rods in a load from one of the documents to which I posted a link earlierhttp://www.ansn-jp.org/jneslibrary/npp2.pdf
says for a typical 1,100MWe class BWR reactor: “BWR fuel assemblies, for an example of 8×8 type, consists of 64 rods: 62 fuel rods …” — Fukushima 1 was an older BWR3 7×7 design.

William, chloride corrosion is not the enemy right now… decay heat and cooling is. Most chloride corrosion studies are over extended periods of time on Reactor Components… not immediate…. thats all I can provide.

Note that presumably, the fuel in the pool in unit #4 was going to be re-loaded into the reactor and is not “spent” in the usual sense of the word.

In that case, would there have been any water in the spent fuel pool? If you’re storing fresh fuel assemblies waiting for deployment, it doesn’t make sense (to me in the absence of further info) to store them in moderating fluid. Perhaps the SFP in reactor #4 was drained at the time this started.

That’s bullshit. You can look up the half-lives. The fast-decaying iodine radioisotope takes months to decay away after fission stops. Check what you believe or find on some blog by referring to a reliable source before copypasting echos.

David Lewis wrote,
“Its now getting controversial to have an optimistic take on what’s happening.”

Well, at this point it seems to me that an “optimistic take” would be “Hopefully the local area (within, say, 50-100 km) won’t be affected too badly, on top of the devastation already wrought by the earthquake and tsunami.”

An “everything’s (comparatively) just fine at Fukushima Daiichi” viewpoint seems to obviously contradict even the limited available data, so I could see how that might be considered “controversial”.

The situation at this point is probably a level 6 on the INES event scale–that means it’s rather serious, serious enough to be counted among only a handful of past events (including Chernobyl, which was level 7). Certainly more serious than the initial comments on this blog would suggest, which were along the lines of “This event isn’t even serious enough for the media to be reporting on”. Due to unforeseen elements (namely the fuel storage pools. [edited personal opinion ad hom unsubstantiated]
When all of the people who were telling you not to worry back when the event was INES level 4 turned out to be too optimistic, would their optimism be controversial when the situation is at or near level 6? Seems reasonable to me.

One of the cores that was in a refuel outage required a complete full core offload. Typically only 1/3 of the cores fuel is offloaded for a normal refueling to the pool. That 1/3 pf the fuel load is typically burned out for about 3 cycles/6 years. Most of the Uranium is utilized. A full core offload means the other 2/3 of the fuel which hasn’t been fully utilized (burned out) is also in the pool.

Facts are out there which unit it was. I don’t currently have a reference to post here and refrain from indicating which unit it was.

NRC recommends evacuation of US citizens out to 50 miles of Fukushima “based on system condition estimates for a hypothetical, single reactor site, 2350 MWt, Boiling Water Reactor, Maximum Dose Value of Total Effective Dose Equivalent of 9.9 rem = 99 mSv, with the “Protective Action Guideline” being 5 rem.

Finrod wrote,
“In that case, would there have been any water in the spent fuel pool? If you’re storing fresh fuel assemblies waiting for deployment, it doesn’t make sense (to me in the absence of further info) to store them in moderating fluid. Perhaps the SFP in reactor #4 was drained at the time this started.”

Well, I can tell you for sure that there was water in the pool when this started (last actual measurement was 84 deg C, but allegedly it was boiling some time later and is presumably still boiling now, if there is any left), and they want water in the pool now (which is why they are trying to deliver water to the unit 4 pool using pumper trucks).

I thought this would be common knowledge for anybody closely following the situation, at this point. I’m actually a little bit stunned at your question.

Regarding spent fuel at #4. All of unit #4’s spent fuel was unloaded from the reactor into the storage pool (which *of course* was full of water!). At the time of the quake, not all of the spent fuel from #5 and #6 was unloaded from those reactors. That’s why there’s more spent fuel in the pool at #4.

Radiation levels for workers. Yes, they have raised the allowable limits, but these are still below the max levels set by regulatory standards.

SO…if the reactor 4 “spent” fuel pool is dry and all of the not-spent fuel from reactor 4 was in the pool at the time of the quake, could that mean there is nothing from stopping the fuel from going critical, melting the zircalloy casings or catching on fire. Once that starts I can’t imagine anyone being able to get close enough to do anything about it. It is my understanding that their is NO secondary containment backup system for the spent fuel pool.

Sorry I don’t have a reference for that info, and no time to dig it up. I think it was late last night (about 14 hours ago) on NHK. They had a very good synopsis of the whole episode with models, charts, and computer graphics.

For a BWR refueling a full core off load is the most decay heat limiting event for a spent fuel pool. Which is likely why the loss of level water level occurred first, even if only due to evaporation, when cooling and makeup to the fuel pool was stopped.

The radiation levels tell the tale…. Have to cover that pool to get back in and combat the other issues…..

William,
Sea water may be corrocive, over a period of months plus. Demineralised water, which I have some experience with over years of involvement with maintenance of demineralised water plants in operating power stations, is at least as aggressive. Surprisingly, it is precisely the purity of demin water that makes this so.

Let’s not worry about salt Vs demin water, when the issue is bulk cooling.

BTW, for those who wondered about blowing the roof above the storage pool(s) away, in my time as a volunteer bushfire fighter, there have been instances where water dropped from a bucket has been used to punch right through hayshed roofs in order to get at the burning hay inside.

A chopper with a 1300 litre bucket, about the size which hung beneath the chopper in yesterday’s photo, might easily do the same. High explosives are not the only way to destroy the roof… HOWEVER, what about the covers?

The sliding covers on the top of the storage pool are probably closed. They would be much stronger. The problem may not be the roof, per se, but the covers.

Back of envelope calculation based on spent fuel pond estimated dimensions 12 m wide by 12 m long with 8 m water freeboard above top of spent fuel = 1152 m3 or 1,152,000 kg water. Heat of evaporation is 2257 kJ/kg. The total heat required to evaporate all this water is 2.6 x 10^9 kJ.

From MIT NSE site, full Reactor 4 heat load after 3 months is about 6.3 MW or 6.3 x 10^3 kJ/s. Time to evaporate all the water is then 4.8 days, just about now.

Take note that no data about reactors 1, 2 and 3, which could be almost as much cause for concern due to the following facts:
1) They also have been without normal cooling since the tsunami at least
2) Like unit 4, the floors where the pools are located have suffered major damage from hydrogen explosions
3) Their control rooms have been inaccessible and may still be inaccessible due to high radiation
4) Temperature measurements by instrumentation may be damaged or battery power to use it unavailable (they were attempting to bring new batteries to the control room of units 3 and 4 when the crews were evacuated last time due to explosions, fire and climbing dose rates)
5) Escaping steam has been recently observed at least from units 2 and 3 and there is no conclusive evidence of where it’s originating from (could be from breaches of reactor containment, could be from the SFP or even both).

I thought this would be common knowledge for anybody closely following the situation, at this point. I’m actually a little bit stunned at your question.

I was familiar with the concerns about spent fuel pool #4. It was the bit about storing fresh fuel which threw me. The reporting on this whole situation has been sufficiently confusing I’m beginning to doubt just about everything I’ve heard so far.

So there is indeed spent fuel being stored there. Very well. And they also store fresh fuel there. Which I’d say would be a fairly minor concern all told.

Boron at this point is a feel good issue in my opinion. Water is what is needed period for the vessels and the pools…. Cover it in water, reduce the rad levels through cooling and shielding. It’s doubtful the reaction it can restart under almost any credible situation.

That statement is based on experience from the other two worst accidents that have occurred previously in the commercial industry, TMI and Chernobyl, where a second critical mass even after core melt was never achieved….

Hank, the sources of which core was fully offloaded are available to all. It’s just a tremendous amount of information I am surfing the net for and screening based on my experience. You can choose to believe my comments or not. I try to link if it’s fresh information I just found…

As my wife said tonight, if this happended here I would be still there…. She cried too…

One, there is more than one fuel assembly in a BWR (!!!). There are many pellets forming one rod, but that’s not what I talked about. There are many rods per assembly and many assemblies per full core loading. If you multiply the number of fuel assemblies with the number of fuel rods per assembly, you will find a number in the tens of thousands of rods in the reactor. Notice the difference between pellets, rods, fuel assemblies, and the full core loading. Bigger steps of clusters.

Two, the fast decaying isotopes indeed take months to decay – and the spent fuel in the fuel point is months old. That’s exactly my point, and why the spent fuel pool is a different radiological hazard than the reactor core assemblies.

I don’t know how many fuel assemblies are present in the spent fuel ponds. Anyone know how much spent fuel in the smaller reactor containments and how much in the big central pool?

If radiation exposure remains at or below the new limits, I am not that concerned for radiation workers as there are natural background levels at this levels. I can’t see how they are going to do that with just 50 workers. Why are they not bringing other workers in from other sites especially Fukushima #2 Nuclear Power Station which is in cold shut down or are they already doing this? I have seen no reports on this. Do they have a remote control robot to bring in the hose to start refilling the SFP? I doubt a human would make it. But maybe they would with a very quick death sentence. What happens when that cold water hits those very hot fuel bundles? There are lots of problems here. It seems in the realm of take a guess.

People who think about laying pipes, cooling the SFPs with firehoses, and generally believing that anything is normal in the reactor buildings should take a long hard look at that before they type any more nonsense.

With the possible exception of I-2, the buildings’ interior is trashed, judging from the force of the explosions as per explosion damage and spread of debris as well as what is visible inside.

There is no factual basis for assuming that conditions will be as if someone had simply pulled the plug in a squeaky clean fuel pool.

Tackling any problem in these wrecks will be as easy as extinguishing fires in WTC1 in the late morning of 2001-09-11… if it had been a plane that carried a lot of uranium that hit the tower, that is.

How would a molten-salt thorium reactor perform assuming all-out failure?
Assuming for example containment starting to fail while the entire building is structurally unsound and full of the trash of an average workday as well as assorted structural elements?

Because it is clear that people will demand answers to the question “assuming an all-out Fukushima-type failure, what would happen to a particular NPP design?”

Not: “Will it stay safe?”

This is the new reality: thinking of what will happen if it DOESN’T stay safe.

Finally getting us news press (ABC News), as identified early in this event here, the spent fuel pools are the worst concern right now. The rad levels as the pools empty inhibit any other damage control operations.

The US Army has Fox vehicles that are used for NBC warfare. I’d think the Japanese probably do too. These vehicles should be able to operate in this environment. I would think they could use them to punch a few holes in the outer building and get a hose or two on the SFP.

Also, since nobody has answered for like 12 hours, I repeat the question:

Do we have HARD DATA that refutes the hypothesis that one or more reactors didn’t SCRAM?

E.g. are the radiation/isotope measurements in line with the Untermeyer/Weill rule, or do they provide evidence for energy levels exceeding the predictions?

My impression is that the energy output until seawater injection differed markedly in I-1 and I-2… I-2 took a longer time to wind up while I-1 was problematic from the start. Yet I-1 has the smallest power output of all the reactors at Daiichi.

Now, one can think of ways how this can happen (different dimensions of RV create different thermodynamic conditions, I-2 already running low when quake struck), but the gut level suspicion would be “I-1 cannot have SCRAMmed completely”.

The prevailing view is that a disaster of almost unimaginable proportions is in the process of unfolding. MSNBC national news chief science reporter Robert Bozell calmly explained that “some say” 1 million people died or will die as a result of what happened at Chernobyl.

People are being told that something very much like the Chernobyl event may happen anytime from now. It is possible the wind could be blowing in the direction of Tokyo when this greatly feared disastrous release of a Chernobyl 1 million death cloud happens.

I’m saying, I’m noticing that a website I’ve posted to in the past is delaying posting the opinion of Dr. Ted Rockwell, Rickover’s Technical Director when under the Eisenhower Atoms for Peace Program they caused the first commercial nuclear power plant to be built.

Ted’s opinion is that the fear of radiation is greatly overstated, that the fears of massive radiation release even after containment failure are greatly overstated, and he has issued a prediction that when the dust settles we’re going to see that in the end the damage to the surrounding region and general population is about what happened at Three Mile Island, because the situations are in essence, similar.

I’m saying it’s getting very weird out there if it has come to the point where people look at an opinion like that coming from a source like that in a situation like this and see it as so controversial the normal posting process has to be modified, as it appears to have been. I expect them to eventually post. I’m just saying it appears to be getting very weird.

That site publishes climate deniers who have no qualifications at all with their optimistic view that a far bigger disaster than anything happening in Japan at the moment, i.e. climate change, cannot happen because they say so, and if you happen to describe such types, not even individuals, but such types, as for instance, “devolving Neanderthals” they won’t post it.

I think it is vital that panic be avoided. Many have said the biggest effect of Chernobyl was psychological. Just one example: a very large number of women all over the EU aborted in fear.

Problem is the elevation level at the typical BWR refueling floor level. It’s not as easy as you think to provide enough pump head or even physically reach to punch that hole….

Pumping the water to that elevation can be done and many US facilities have already staged portable pumpers than can achieve the necessary head to reach the refuel floor should all other systems fail (ie 911/station blackout)……… But someone still has to get there to finish the job……

Deaths from this event no matter how bad it gets over time will not likely exceed those in Cherobyl. The Tsunami has wiped most of the local area out and they are already deceased or evacuated since the event started… The water preceeded the events unfolding may have been a blessing…

To answer Amadeus and others here who are questioning, Dr. Jaczko has a Doctorate in Physics and has been a member of the U.S. NRC since 2005. His primary emphasis as Chairman has been on nuclear safety according to the U.S. NRC website. President Obama elevated him to chairman in 2009. I would afford him a lot more credibility than I do to Wikipedia, which some commenters here are turning to for expertise.

Killing millions, we’ve been told that for decades. So far 0 radiation related deaths by the nuclear plants in Japan, all primary drywell containments intact, decay heat down to 0.2 percent full power.

Chernobyl has no full containment, had a bad reactor design that caused 10000% power, and a graphite chemical burning on top of that. That’s some serious drive of radionuclides into the environment, which by design and by physics simply arent there in the Japanese situation.

Update on Daiichi unit 4 spent fuel pond: water temperature rising, but not yet to boiling point. So it appears the trouble is at reactor 3 then?

@John: well you are correct insofar as that if bulk cooling does not work, the seawater’s corrosiveness is not a relevant issue anymore.

However, a more correct way to put it is: there won’t be any problems less significant than those caused by seawater corrosion.

Until the cores have cooled and/or until the facility has been physically cleaned up and decontaminated and repaired to a modicum of functionality, corrosion will occur.

The real “fun” stuff will be waste disposal.

It would be much easier if as much corium/NF would escape into the atmosphere. Particularly regarding any RVs that remain intact, as long as heat and pressure have not bled off. If you have ever found an egg that had been left in the sun for a few weeks and shaken it, you’ll know what I mean.

The next 3-4 months, a lot of people will be facing a lot of tough questions
[edited personal opinion off topic]

@rpl: only fools use Wikipedia as a source of reference. Smart people use it as a source FOR references, which tend to collectively outweigh the experience of one single scientist, no matter how eminent.

in the short term (for the radiation workers in hazmat suits)
1) we can ignore alphas, which are heavy particles (essentially a helium nucleus) and can’t penetrate well. The only way these become dangerous is if ingested. Then they are the worst of all types, because they have so much energy, and deposit it all to a small areas.
2) beta negative decays (electron produced) can penetrate a bit more (like 1 cm of people) so in a suit, it shouldnt have a great effect. The suit itself plus the air gap inside the suit should make up for it.
3) beta positive decays (positron release) create gammas almost immediately
4) gamma rays are highly energetic and highly penetrating. There is no way to protect against these. If they are more energetic than low end Xrays, lead wont do much either. If I am right, these will largely be formed by beta positive decays, plus some isomeric transitions.
5) The interactions of some of these particles with other matter will probably generate xrays via various mechanisms – bremsstrahlung and compton scatters of gammas etc. Xrays of high energy can penetrate very well. If this makes a large component of the radiation then lead vests would help a lot, if the energies were low enough.

So for the workers at the plant.we need to know what % is alpha/beta negative, and what percentage is a gamma source. We also need to know what amount of xrays there are and what energy they are

Then, we get to the other side of things. For the public, long term, it flips. The alphas generators are long lived so they can bioaccumulate, meaning they can contaminate food and get inside people. This is the major public health risk. The other risks (betas, gammas, xrays) are significantly less, although still present.

It means that you have a different apporach. For the workers, they are safe from alphas if they wear suits and masks (with oxygen). The public later need uncontaminated food and water to stay safe, and if there is radioactive substances spread around it is almost impossible to stop it getting in people.

If some nuclear scientist (I only know the effects on humans well) could answer the question as to the percentage make up at this stage of the radiation levels by alphas, betas and gammas, and xrays, that would be great. 100mSv might effectively only be 10mSv for the workers, or it could be 90 mSv.

“(Reuters) – The level of radiation detected at the Tokyo Electric Power Co Fukushima plant has fallen steadily over the past 12 hours, an official at Japan’s Nuclear and Industrial Safety Agency said on Thursday.

A level of 752 microsieverts per hour was recorded at the plant’s main gate at 5 p.m. (0800 GMT) on Wednesday, said the official, Tetsuo Ohmura. The monitoring point was then changed to the plant’s west gate and readings were taken every 30 minutes, he said. At 5 a.m. the reading was 338 microsieverts per hour.

That level was still much higher then it should be, but was not dangerous, and that by comparison absorption of a level of 400 was normal from being outside over the course of a year, Ohmura said. (Reporting by Terril Jones)”

William Fairholm wrote,
“If radiation exposure remains at or below the new limits, I am not that concerned for radiation workers as there are natural background levels at this levels. I can’t see how they are going to do that with just 50 workers.”

Well, with dose rates at the _front gate_ of the site at 3+ mSv/hour, presumably higher closer to the source, it seems like there is an issue. If they were already close to 100 mSv when the limit was raised (so that they could continue working), that gives them 50 hours at 3 mSv/hour before being legally “dosed” again. A “suicide charge” would probably result in much higher doses, and render the term an apt description.

I watched an interview earlier of a volunteer firefighter from the site. We all need to keep in perspective what has happened overall there. He was finally being pulled back, he was in complete tears and said his home and entire family was lost/missing from the tsunami. How many days has this man been there fighting the battle, yet he stayed….

“… Only the General Electric design has survived. … GE BWR Fuel Assembly. Fuel Assembly: 8 ´ 8 array; Number of Assemblies: 746 … BWR control rods are always placed at the bottom of the reactor rather than at the top as in the case of …”

Affirmation that a million died as a result of Chernobyl immediately consigns the remainder of David’s contribution to the waste basket. I can understand people relying on WHO reports (for example) of the order of 5000 deaths, but where is a citation for 200 times that?

This thread benefits nothing from wild statements… the actual facts as they evolve have been sufficiently confronting and surprising. There’s no need to make stuff up.

To then refer to TMI and its zero deaths as being comparable, Ted Rockwell or no Ted Rockwell, is confusing in the other direction. David, was your message meant to be that the Japanese struggles will lead to no significant contamination beyond the power station fence and no radiation-induced deaths at all?

I’d be interested to read informed opinion about what is actually happening (facts as they evolve); analysis (explanation of those evolving facts in order to understand the current situation); and further analysis, as Barry and some others have provided, to indicate where they believe this might be heading and how fast – scenario outlines, if you will.

What we do not need is an uncited extreme minority opinion about an imaginary Chernobyl head count.

A fuel assembly is an array of fuel rods, the design of that assembly, the loading of the fuel rods or moderator rods (water) and actually burnable neutron poisons is an art.

Trust me on this if you can, fuel assembly or rod design is not the concern now. To fully explain this would require a complete understanding of reactor kinetics and fissionable or non fissionable material.
Let alone critcal geometry…. Way beyond most that are reading this blog….

Fission product decay heat remains the enemy imediately, fissionable products or their production daughters is secondary for now…. Cooling and shielding is paramount.

During my reading of the latest JAIF pdf which is now quite old, trying to find if they are injecting salt water directly into the core pressure vessel I did not look at the statis of the all the spent fuel pools. Number 3 spent pool is also low (or dry, who knows). 5 and 6 temp is increasing and they have no imformation on 1 and 2. I would guess evaporation has dropped their levels too. So we may eventually have 6 dry spent fuel pools.

Slide 12 of that Oregon State ppt has the individual fuel rod shown — no scale provided but the fuel rod is shown as containing six or seven pellets each about 1cm tall. Tiny things. The image is cited to “WASH-1250” and the text on the page says:

The oregon state reactor is a test facility, BWR fuel rods and assemblys are significantly higher and contain alot more fuel pellets. That information is available, but not going to take the time to link it now as it is relatively unimportant….

Absolutely right. No real world experience strictly government and academia.
He’s an Obama appointee From his bio –
“Immediately prior to assuming the post of Commissioner, Dr. Jaczko served as appropriations director for U.S. Sen. Harry Reid and also served as the Senator’s science policy advisor. He began his Washington, D.C., career as a congressional science fellow in the office of U.S. Rep. Edward Markey. In addition, he has been an adjunct professor at Georgetown University teaching science and policy.”

em1ss: No, it’s an … Englishism I guess. I was absolutely seconding your post about how our prayers should go out for those fighting at the plant. Thought it was a fine thing for you to disentangle us a bit from the … mechanics of what’s going on and remember the human.

So hear hear again!

(Was originally “Hear him!, hear him!” back in the 1800’s I guess. Is now just a general cheer of hearty support.)

I analysed a bit the situation of the housing of reactor 3, as it can be seen in the photos of the 16.th of march 2011.
I made a sketch about it, with a photo and a cross-section of a Mark 1 reactor.
You can see it here:

What is interesting is that, in the photo, on the left, there is a dome that can be seen between the debris of the roof metal structure. The big question is: what is that dome? if it is “A” (concrete lid of the concrete confinement) it is ok, if it is “B” (metal dome of the upper part of the metal confinement of the reactor) than it is… bad.

You know in my wildest imagination I would not have believed that during a loss of cooling event (actually events), that the main concern may be the spent fuel pond and primarily one for a reactor that was not even running and has no loss of cooling. Murphy, Murphy, Murphy, you have certainly gone into overdrive in this one. Sorry, but I’m a little dumbstruck and certainly hope I’m overreacting (pun not intended).

@Cyril, I followed your link and the Reuters stories were both framed as “Tokyo Electric Power Co. spokesman said”. I sincerely hope the information is correct as the source seems to have been serially unreliable throughout this event.

@Mike, you should listen to @DV82XL, who isprobably a perfectly reasonable guy in person who just has an unfortunate tendency to make personal attacks on people on Websites. By all means take his advice and study up on radiation thoroughly by reading Wikipedia. Only dare comment on Websites if you can follow his exemplary path and agree with him in all things.

Yes, these docs aren’t describing that teaching reactor, they’re describing the early boiling water power reactors. Quote from that last link I posted, which is “A Guidebook to Nuclear Reactors, Anthony V. Nero Jr., May 1976, Lawrence Berkeley Laboratory”

“There are two types of ECCS available. As soon as the water level drops below a preset minimum, a high-pressure injection system driven by steam turbines is activated. Backing this up are low-pressure electrically- driven core-spray and coolant-injection systems, which would become operative after failure of the high-pressure system to cope and subsequent depressurization
(through pressure relief valves) into the dry well and downcomer arrangement. The low-pressure systems are sized to handle the reactor decay heat without damage to the core.
The steel dry well, and the reinforced concrete structure immediately surrounding it, are enclosed by a secondary containment building (Fig. 2-12). Gas exhausting from this building passes through multiple filtration systems for trapping volatile radioactive species. In addition to an altered suppression pool arrangement, as mentioned above, more recent BWR systems have another leak-tight containment structure between the primary containment and the reactor building.
In more current models, a suppression pool is still used, but it does not take the form of the downcomer-torus arrangement….”

Rev. Mod. Phys. 47, S1–S123 (1975)
Report to the American Physical Society by the study group on light-water reactor safety

“The issue of light-water reactor (LWR) safety has been the subject of a part-time, year-long study sponsored by the American Physical Society. The goal of the study was the assessment of some of the technical aspects of the safety of large light-water nuclear power reactors typical of present commercial practice in the Unted States. The report examines issues related to safe operation of LWRs; the research and development program responsible for establishing and enhancing safety; and the consequences of accidents for public health and welfare. The report in no way deals with the need for nuclear power or its benefits, and should not be considered as a net assessment of the risks versus the benefits of nuclear reactors. Since the risks of ecological impacts of other energy technologies are not addressed, no recommendations are made concerning the specific reactor program which should be followed in the immediate future. Among the areas covered in the report are primary pressure-vessel integrity; quality assurance; accident initiation from operator error, transients, and sabotage; the adequacy of present emergency core-cooling system designs; the calculation of long-term consequences to health of one particular low-probability accidental release of radioactivity; and the experimental and calculational (computer-code-development) aspects of the present reactor safety research program. A number of recommendations are contained with the report, mainly addressed to ways in which the safety of the present LWRs can be improved or better understood.”

Apparently there are some indications the floor of the SFP on I-4 has cracked (n-tv via unspecified Japanese media).

US is gonna deploy a Global Hawk RPV.

Russia preparing evacuation of diplomatic personnel.

Elsewhere, the first tsunami/quake evacuees are returning home. In fact, it may be that 30% of the non-Fukushima evacuees are already leaving the emergency shelters from the figures I have seen today.

Cleanup in the hardest-hit areas is stalling due to a general lack of personnel, material and infrastructure. In the less seriously affected areas, the shaky power supply is the biggest problem remaining.

1) When the earthquake struck the reactors automatically started to shut down (control rods fully insterted)
2) All OK until tsunami struck when mains power lost and diesel backup did not work, so affecting the cooling.
3) Batteries then kept cooling going until they went flat.
4) All the problems resulted from lack of power which affected the cooling. So if mains power had been maintained there would have been no problems.

Therefore once it was known reactors OK after quake, but no power after tsunami, would it not have been an idea to restart one reactor so as to provide power to the whole complex? Surely this could have kept all the cooling going and prevented many if not all the problems now faced?

I am layman in all this so sorry if this is a silly question, but I am interested to learn and comments from the learned folk here would be appreciated.

Nikkei, on 17 March 2011 at 10:03 AM said:
Japanese Police are getting ready to use vehicles with water cannons mounted to spray water into spent pool in reactor 4.

If this is not done initially as a fine mist to evaporatively cool the fuel rod there is going to a lot of stress cracking. But maybe the bundles are hot enough to react with the water for another hydrogen explosion. Already happened when it was going dry so even more likely now as they would be hotter. Has to be done, but there is going to be a significant release of radiation.

@ew3, you seem to want to drag American Politics into the discussion. While I don’t think it is fit for prolonged discussion here, you must be aware that the Obama administration has remained supportive of Nuclear power throughout this Japanese crisis, even while disappointing the left fringe of his political base. It has been the U.S. Republican party and House Speaker Boehner who are having trouble freeing themselves and their hands from the pockets of Big Oil, who have been publically Anti-Nuke lately.

Hello, I live in Tokyo, around 250kms away from Fukushima.
Again, I would like to ask your opinion on how dangerous it is to stay here. I understand the worst-case scenario for me would be a fire or explosion exposing the rods, releasing a large amount of radioactive particles into the air, and a wind carrying those particles to Tokyo. If this happens, what is the probable level of hazard to my health?

Friend or Foe to Nuclear power, I have to believe what Jazko said for now, more than I believe media reports from Japan….

Don’t take this as fact, it’s just my analysis of how we got to where we are….

People also should realize that the entire nuclear industry is scrambling right now because of this event. Checking things are in place for similar events and trying to figure where this all went wrong.

Problem still remains that a beyond design basis accident (DBA) occurred in the earthquake followed by a beyond DBA tsunami which caused a beyond DBA station blackout (complete loss of AC power).

It should be evident that the early designs of these reactors would not have consider these events to occur together. Station blackout is a relatively new concern with respect to when they were designed.

An obvious weak link so far from this event is the need to be able to direct vent any BWR containment design directly to the exhaust stack. This is needed to reduce containment pressure and prevent primary containment failure. The observed hydrogen generation during a loss of power without injection seems to be underestimated by design.

Because of it’s limited size, volume and heat removal capability, the Mark 1 Containment was already predicted to be the most suceptable to failure due to heat generation and pressure rise. Again, the hydrogen pressure rise may have not been fully anayzed for the concurrent events experienced….

All other previous methods to address hydrogen generation require power or emergency power. In severe accident management procedures venting it to the secondary containment (reactor building) is proscribed.

The intent here was to holdup the fission product gasses for decay prior to release to the atmosphere. They would be somewhat scrubbed by venting steam below the water line in the suppression area and decay in the Reactor Building volume would only help prior to release.

These methods may have worked, if power was available for ventilation fan operation in the secondary containment (reactor building) facilitating dilution of the hydrogen generated without design comp measures due to loss of power…

It appears in this case, it resulted in hydrogen explosions in the secondary containment (reactor buildings), possibly in the primary containments (torus) which now exposed the final weakness we are seeing in that of spent fuel pool cooling.

@em1ss note that among the acutely affected reactors (fuel pool temps do not seem to be stable in I-5 and I-6 either) only I-1 – the least problematic at present – is a BWR-3. The reactors in the most serious condition are all BWR-4 (which is still a 1960s design).

But as it looks, the 1970s BWR-5 design of I-6 does not seem to be much less susceptible to the SFP problem.

Where does the unstable water temperature in the I-5 and I-6 SFPs come from? Ambient radiation? We know it’s there, but is it sufficient or would it heat the SFP contents less than their capacity to bleed off excess heat? Probably can be roughly calculated if the composition of ambient radiation is known.

Thanks to em1ss and other informed contributors. I thoroughly appreciate your input and I’m sure others feel the same.
There will be a lot of learnings out of this event no matter what our individual views on nuclear power. I salute the herous on the ground trying to bring the situation under control.

@Nikkei: first, the question of feasibility. As the remote-sensing and ground-based imagery shows, it is a mess all around the SFPs of I-4.

So it is not obvious whether the water cannons can actually reach anything worth reaching.

Second, the question of SFP integrity. If I understand it correctly, the temps are not high enough and there was not enough “white smoke” (read: water vapor) to explain the low water levels in the I-4 SFP by boiling-off.

So if the SFP is structurally damaged, watercannons are not much help.

And third, the problem of unclear fuel status. Putting water on top of fuel rods whose zircaloy cladding is already buckling and breaking is dangerous enough; spraying it on top of them with a high-pressure nozzle is liable to create a situation which according to many eminent scientists are “impossible”.

I’m out, it’s time to sleep and deal with addressing the emergent industry wide issues tomorrow… In perspective, that’s still a whole lot easier than what those that are fighting the fight in Japan currently are dealing with.

Do we have data on the amount of fuel in the SFPs? Was some of it transported offsite or are there indeed 30 years’ worth of fuel elements stacked (or probably not really stacked well anymore) up there?

And don’t forget the other problem the 1960s designers wouldn’t have thought about
— human factors issues with these old plants, well documented and fixed in newer installations
— these plants as tired old equipment due to be taken out of service, Unit 1 _this_month_.
— operation during an unimagined crisis by human beings many of whom don’t even know where their families are.

I, too, am off. Thanks em1ss, Prof. Brooks (P.S. my post above that received the edit-stick was not intended as an ad hominem attack, for the record–I try to keep things respectful), and all. I learned a lot from this discussion, but unfortunately pressing matters will keep me away until after the immediate incident is (hopefully) resolved.

The only other thing that I’ve been thinking about is, even once (if) power and pumping are restored, even once water is in the storage pools, the incident is still not over. That seems to be only the beginning of the end, with more releases of steam (at best) inevitable as the cooling process proceeds. I certainly hope for nothing worse than we’ve already seen.

@mike – I only know you from what you write, and don’t tell me that these threads haven’t been full of many that don’t have the faintest idea what the difference is between prompt radiation, and radioactive contamination.

Nuclear Power Plant Safety
by H.J.Otway
… probability of large-scale accidents. This article will limit itself to a discussion of the latter item, consistent with space limitations, based largely
upon a summary of material from the USAEC report WASH-1250 [ 1] “The Safety of Nuclear Power Reactors (Light Water Cooled) and Related Facilities”…. an up-dating of the WASH-740 material, also presents the basic design philosophy for assuring nuclear power plant safety —”defence in depth”.

This philosophy defines three levels of safety:
The first level is to design and build …

The second level … to prevent or minimise the effects of an incident. Such devices include an emergency core cooling system (ECCS) to provide adequate core cooling in event of a loss of coolant accident, …. an independent supply of off-site power.

The third level of safety supplements the first two by features which add design margin by assuring protection of the public even if seemingly remote and unlikely events occur. … such as the assumed independent failures of redundant protective systems simultaneously with occurrence of the accident they were designed to control. … Other third level design features include protection against (among others) seismic events, tornados, floods, component failures.

It should be mentioned that there has been a controversy surrounding emergency core cooling systems since semi-scale tests in 1969 indicated deficiencies in the evaluation models and computer codes used in their design. … ECC systems must satisfy required performance criteria under conservative assumptions regarding simultaneous component malfunctions…”

Based on a press release from the Japanese Chief Cabinet Secretary dated 16 March 2011, the IAEA can confirm the following information about human injuries or contamination at the Fukushima Daiichi nuclear power plant.

Please note that this list provides a snapshot of the latest information made available to the IAEA by Japanese authorities. Given the fluid situation at the plant, this information is subject to change.

Injuries

* 2 TEPCO employees have minor injuries
* 2 subcontractor employees are injured, one person suffered broken legs and one person whose condition is unknown was transported to the hospital
* 2 people are missing
* 2 people were ‘suddenly taken ill’
* 2 TEPCO employees were transported to hospital during the time of donning respiratory protection in the control centre
* 4 people (2 TEPCO employees, 2 subcontractor employees) sustained minor injuries due to the explosion at unit 1 on 11 March and were transported to the hospital
* 11 people (4 TEPCO employees, 3 subcontractor employees and 4 Japanese civil defense workers) were injured due to the explosion at unit 3 on 14 March

Radiological Contamination

* 17 people (9 TEPCO employees, 8 subcontractor employees) suffered from deposition of radioactive material to their faces, but were not taken to the hospital because of low levels of exposure
* One worker suffered from significant exposure during ‘vent work,’ and was transported to an offsite center
* 2 policemen who were exposed to radiation were decontaminated
* Firemen who were exposed to radiation are under investigation

The IAEA continues to seek information from Japanese authorities about all aspects of the Fukushima Daiichi nuclear plant.

Annotated satellite picture, buildings identified:
“The angle of this new image, however, shows what appears to be more extensive damage to the Unit 3 reactor building than can be seen in previous satellite imagery. The image also shows damage to the reactor building for Unit 4 from an explosion. Steam can be seen venting out of a hole in the side of the reactor building for Unit 2. Workers likely removed a panel in the side of the building to vent the steam.”

Nikkei, on 17 March 2011 at 11:43 AM said:
“Hank the second plant had the same tsunami issues as it a little to the south of Fukushima Daiichi.

They had problems with keeping power to the cooling but they were able to fix the issues.”

I think the main factor is they did not lose links to outside power. Would be somewhat interesting to know if they lost their backup generators, but I doubt they did. Most likely the tsunami was not as large due to local sea bottom characteristics, otherwise outside power would have been lost.

“A fuel assembly is an array of fuel rods, the design of that assembly, the loading of the fuel rods or moderator rods (water) and actually burnable neutron poisons is an art.

Trust me on this if you can, fuel assembly or rod design is not the concern now. To fully explain this would require a complete understanding of reactor kinetics and fissionable or non fissionable material.
Let alone critcal geometry…. Way beyond most that are reading this blog….

Fission product decay heat remains the enemy imediately, fissionable products or their production daughters is secondary for now…. Cooling and shielding is paramount.”
===
I agree to some extent. But its an interesting discussion on a blog with many nuclear engineers reading and posting.

I’m wondering about reports that say criticality in is still a possibility in one or more of the cores. How may that happen and how unlikely? U-235 needs a flux of thermal neutrons as well as proper geometry to sustain a chain reaction. Heat (which we obviously have) causes doppler broadening of the U-235 cross section to increase the probability of neutron absorption. Water is a good moderator to slow the neutrons, which allows some new fission reactions of the U-235. So it must be the control rods that prevent enough thermal neutrons from being available to sustain the reaction??? I’m interested in a technical discussion about why criticality may or may not be possible.

I’m not trying to make the case for possible criticality, I’m just technically interested in the reason why its so unlikely.

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If you wanted to aggravate the potential for panic what you’d do first, after tolerating the exaggerated uberhyped concern for radiation you knew made no sense all these years, is undermine the confidence of the population in Japan in the statements and abilities of their own officials and engineers.

After this is over we’ll find out if the Americans are right. Even if the NRC assessment is the correct one what did he contribute to the situation by making his views public before convincing the Japanese leadership?

A commenter at Rod Adams blog, “Rich” says this: “Are you aware of the fact that the whole “hydrogen bubble” hysteria at TMI was caused by an NRC “engineer” (in headquarters, not at the site) that used the conversion factor for English/metric backwards? He was “checked,” etc., by other NRC engineers and thus they firmly believed in their conclusion. Meanwhile, we at TMI spent three days trying to convince the NRC that something was wrong with their calculations. We finally came up with the simple equation PxV=PxV (any basic chemistry student understands that) and after a series of pressure changes we provided the proof that the “bubble” in the core was of no concern. By then, evacuation orders were issued, people panicked, etc, etc, etc. Of course, the responsible NRC engineer was promoted, and now you know the rest of the story. How much of that is going on now? (I know – I was there and have the T-shirt to prove it)”

Its one thing for the NRC to blunder around on their own territory, but to wade into the middle of this crisis as Jaczko has done with his Congressional testimony seems tragic.

There is a very good possibility that the NRC does not have any on the ground insights in this case. The spent fuel pool for unit 4 was reported to be at 183 degrees and full on March 15. Where did 23 feet of water above the 14 foot long fuel assemblies go?”
[ ad homs removed]

Exactly right. Every time I hear someone making comments I look them up via google. By and large they are poli-sci majors. In this case he has a legitimate degree, but if you review his politics and what he has done since getting his degree you come to the conclusion he’s a bomb thrower.

I suggest we check on every person with an opinion and check their background and political persuasion.

This should put the loads of values from all sorts of measuring sites into perspective. With the data above and the date/time, you can now make a good guess where a particular measurement was taken exactly (perimeter, close to reactor buildings, inside reactor buildings).

Yes I don’t understand the temperture readings from IAEA and the claims that the spent fuel ponds are dry. But there is a lot of effort to refill them and JAIF reports low water level on 3 and 4 and suspected fuel damage. I find the same reading on both days not credible for unit 4. The temperature should have been rising. No data at all for units 1 and 2. Why?

@David Lewis “There is a very good possibility that the NRC does not have any on the ground insights in this case”

“The information that we have is coming from staff people that we have in Tokyo who are interfacing with counterparts in the nuclear industry in Japan, and I’ve confirmed with them that they believe the information they have is reliable,” Jaczko told ABC News.

“We believe that there is no water in the spent-fuel pool known as No. 4, and I would say that it is my great hope that the information that we have is not accurate,” he added.

‘They need to stop pulling out people—and step up with getting them back in the reactor to cool it. There is a recognition this is a suicide mission,” the official said.’

Is this really what the US government thinks ?
==========
That’s a really bad quote, the part about “suicide mission”. ALARA, “As Low As Reasonably Achievable” still applies. They’re doing a great job managing a difficult circumstance. But its not a suicide mission.

William Fairholm, on 17 March 2011 at 12:46 PM — I will hazard the guess that the pools of units #1 and #2 contain no fuel rods. For unit #1 this makes sense since it was due to be decommisioned later this month and so had already received its final refueling some time ago. For unit #2, one might check for something similar.

“ew-3: a scientific question must not be decided based on someone’s persuasion, but on their data.”

Absolutely right. I’d like to hear the data the had the head of our NRC had.

Odds are he had no data.

Once you get inside the beltway facts become secondary. He moves ahead in his career by closing down nuclear as an option. (Google him and you’ll see what I mean). I grew up in the 1950s/60s when we made stuff happen.

The reason they concentrated on I-3 is that yesterday there was still water in the SFP, with no data suggesting this has changed yet. Whereas in I-3 the SFP water seems to have boiled off for the most part. But due to the wreckage it is hard to tell. (source: NHL)

“Therefore once it was known reactors OK after quake, but no power after tsunami, would it not have been an idea to restart one reactor so as to provide power to the whole complex? Surely this could have kept all the cooling going and prevented many if not all the problems now faced?”

I like your way of thinking, it is “outside the box” so to speak. But the pumps, controls, valves, etc. required to produce power but which do not serve a safety purpose cannot operate unless mains or local generator power is already available. They draw a lot of energy and would not be powered by the batteries. Also, there is a good chance that circulating water pumps for the turbine condensers were located near the ocean and damaged by the tsunami.

“…Japan now faces a question that has been taboo since the Chernobyl nuclear accident in 1986, namely, who has to step up and do the work to mitigate a high-radiation nuclear accident”

He writes that the topic came up in Japan after everyone saw the sacrifice of the Chernobyl “heroes”. He notes the debate “faded because it would have involved the fundamental social issue of whether a democratic state can order people to do work harmful to their health.”

“There was also the myth that major accidents just do not happen in Japan.

Now, however, we face an emergency situation. A quick decision and response is required.”

Looking at the helicopter, comparing the water pattern to what you see from firefighting operations, they’re making a fairly high speed pass across the top of the reactor building. It must be very hot.

This is where we need the damn robots. One to hover the helicopter with the huge bucket of water, or lower it right through the roof; the other to rappell down, put the hose in the pool, tie it down, and signal to start draining the bucket through the hose.

@Hank: the technology you describe does neither exist, nor would it work reliably under these conditions anyway.

From the TEPCO reports on I-4 SFT water level (it can be verified but neither regularly or at will; it is more like chance observations) and ceiling status (now reported as having been collapsed), it is obvious that the SFT floor is full of debris.

Add to that radiation levels which will make short work of unshielded electronics. Shielding makes a RC vehicle heavier, bulkier and harder to control.

The US federal government military R&D budget is around $80 billion a year, with Health R&D at $27 billion plus. R&D for those robots that could be delivering water to those pools right now might have amounted to a rounding error in the military R&D.

It used to be said of Japan that they had more robots working in industry than any other country.

@David yes if anyone had such machinery, it would be Japan. But even Japan is still bound by the usual laws of physics. Conservation of momentum, conservation of energy. These are the two bad guys in this case, and have been from the start.

But they won’t ever go away. Not in this universe they won’t. No matter how much money you throw at them. Fundamental laws of nature cannot be bought or bribed.

It is actually rather simple:
Before there will be a single robot/RC vehicle for NPP rescue work, there will be thousands for nonnuclear rescue work, e.g. after earthquakes, tsunamis…

Presently there are about zero of the latter in use, hence there are also zero of the former to use.

Black start of a unit in order to run the others would require about 10MW, perhaps more. Batteries, etc, are OK for run-down but useless for startup.

Put bluntly:
1. A unit cannot be started without connection to the grid to provide start-up power for auxiliaries – fans, pumps, computers, miscellaneous power and lighting, and instrumentation and control systems.
2. To keep a unit running requires a connection to the grid, which provides sufficient stable load for the unit to work with. An adjacent nuclear power plant or three would not provide an adequate load, even if switching and conductors could be arranged, which I doubt.

As a sanity check, here are some claims excerpted from the parallel discussion over at BoingBoing:

Brace yourself:

If that sounds like a design flaw, you’re right. The Fukushima reactors were built in the early 1970s. In modern nuclear reactor designs, pumps aren’t necessary to move water through the core in an emergency shut down. Instead, the water moves via gravity.

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. Like Maggie said, these are a 1970’s design. Chernobyl in 1986 made everyone fundamentally change their plant design so that in the event of a failure, or a problem, the system cools itself. Since then, Reactors are made to always run on the ‘cool’ side of their reactions and the human intervention is to keep them ticking over. This is very important to consider when talking about say, new nuclear power plants being built – for example nobody would but a boiling water reactor these days.
Like Maggie said the coolant is ideally gravity-fed rather than pumped, so if anything goes wrong the coolant still flows down and it all works. From
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Actually unattended nuclear power plants, assuming they don’t get flooded like the Japanese reactor, will eventually just shut themselves down. A couple of things happen.

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I could go on and on, but am already making this more complicated than most people care to deal with.
Oh, as a side note to someone else’s comment, control rods slowly change into atoms or isotopes that don’t absorb neutrons. So if not maintained, eventually a reactor core will heat enough to melt down.
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wow! this is an awesome explanation!

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All modern reactors come with automatic shutdown mechanisms when there is a problem. But they are pretty good at running themselves, so what would more likely happen is that they would operate until they ran out of fuel and shut down when there was no one around to refuel (like a car running out of gas, it would just putter to a stop).
Modern reactors also are designed such that they will shut down in the event of loss of coolant (albeit this can take some time when you’re at the GW+ scale), and have a maximum achievable power. This is guaranteed by the laws of physics in what is called a “negative temperature coefficient” if you want to look up the details.
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That was the shortest, clearest explanation I could even imagine. Thanks for the info, but more than that, thanks for putting my mind at ease. Now at least I’ll know how to interpret the stories that follow.

NHK reports 14 deaths during evacuation due to insufficient medical supplies. I have also seen reports of “another explosion at I-4” supposedly on NHK, but there was no mention of it on the program so I supposed it was referring to past events.

What was the thinking behind putting several reactors together like this? Could it not have been foreseen that if one goes into a state that makes the facility unapproachable, then the rest of the plant can’t be looked after. If one explodes for whatever reason it might damage another reactor. It all seems like the temptations of nuclear mist the glasses of those who should know better. I am of limited education and it seems like a no brainer thought.

In the JAIF pdf listed above by chavv, the main change from the last is that they are now listing the Reactor Pressure Vessel Integrity as unknow for units 1-3. Radiation levels at the NPS border has fallen again, which is good, but they must be fluctuating quite a bit with just wind patterns is I don’t know what to make of a single number given every 8 hrs or so.

NHK reports they managed to spray water but still the temps in pools of #3 and 4 reactors are increasing.

” The forces finished the 30-minute operation on Thursday evening. Five fire engines loaded with a total of 30 tons of water were used.

But the Defense Ministry says it has not confirmed whether the water reached the storage pool housing spent fuel rods, though it reached the inside of the building that houses it.

The forces are preparing to repeat the exercise on Friday if requested by the government.

Temperatures are rising in the spent fuel rod pools of the plant’s No.3 and No.4 reactors, where a massive radiation leakage is feared.

Earlier in the day, police also used high-pressure water canons to douse the No.3 reactor from the ground. But the water failed to reach the target, and the operation was suspended due to high radiation levels.

Are there no gasoline driven pumps at the major Japanese steel mills in the south that can be airlifted to the site? There’s gotta’ be some pumps somewhere that aren’t electrical driven. Even some small trash pumps would add more water than those chopper drops – that mostly miss the target!

How can they be sure that even with a new power feed those tsunami-hit pumps and the connections and level 2 controls will even work ? Who is developing some contingency plans with air lifts of replacement or alternate pumps? After four attempts – this is starting to look like a 3-ring circus.

“… On Wednesday, when the American Embassy in Tokyo, on advice from the Nuclear Regulatory Commission, told Americans to evacuate a radius of “approximately 50 miles” around the Fukushima plant, the recommendation was based on a specific calculation of risk of radioactive fallout in the affected area.

In a statement, the commission said the advice grew out of its assessment that projected radiation doses within the evacuation zone might exceed one rem to the body or five rems to the thyroid gland. That organ is extremely sensitive to iodine 131 — another of the deadly byproducts of nuclear fuel, this one causing thyroid cancer.

The commission says that the average American is exposed to about 0.62 rem of radiation each year from natural and manmade sources.

The American-provided instruments in Japan measure real levels of radiation on the ground. In contrast, scientists around the world have also begun to draw up forecasts of how the prevailing winds pick up the Japanese radioactive material and carry it over the Pacific in invisible plumes.

Private analysts said the United States was also probably monitoring the reactor crisis with spy satellites that can spot the heat from fires — helping it independently assess the state of the reactor complex from a distance. …”

from the BBC site:” Japan has started using a cooling pump at the Fukushima plant’s stricken reactor 5, according to several reports quoting the Japanese government. It is thought to be a diesel-powered pump, rather than a device powered by the still-to-be-reconnected electricity supply.”